Save away the environment variables we rely on

There are cases when we overwrite %ENV values, and while this is
perfectly fine on some platforms, it isn't on others, because the
Configure script isn't necessarely run in a separate process, and
thus, changing %ENV may very well change the environment of the
calling shell.  VMS is such a platform.

Furthermore, saving away values that we use also allow us to save them
in configdata.pm in an effective way, and recall those values just as
effectively when reconfiguring.  Also, this makes sure that we do use
the saved away values when reconfiguring, when the actual environment
variables might otherwise affect us.
Reviewed-by: NAndy Polyakov <appro@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4818)

Configure

@@ -223,25 +223,12 @@ if (grep /^reconf(igure)?$/, @argvcopy) {
 	    @{$configdata::config{perlargv}} : ();
 	die "Incorrect data to reconfigure, please do a normal configuration\n"
 	    if (grep(/^reconf/,@argvcopy));
-	$ENV{CROSS_COMPILE} = $configdata::config{cross_compile_prefix}
-	    if defined($configdata::config{cross_compile_prefix});
-	$ENV{CC} = $configdata::config{cc}
-	    if defined($configdata::config{cc});
-	$ENV{CXX} = $configdata::config{cxx}
-	    if defined($configdata::config{cxx});
-	$ENV{BUILDFILE} = $configdata::config{build_file}
-	    if defined($configdata::config{build_file});
-	$ENV{$local_config_envname} = $configdata::config{local_config_dir}
-	    if defined($configdata::config{local_config_dir});
+	$config{perlenv} = $configdata::config{perlenv} // {};
 
 	print "Reconfiguring with: ", join(" ",@argvcopy), "\n";
-	print "    CROSS_COMPILE = ",$ENV{CROSS_COMPILE},"\n"
-	    if $ENV{CROSS_COMPILE};
-	print "    CC = ",$ENV{CC},"\n" if $ENV{CC};
-	print "    CXX = ",$ENV{CXX},"\n" if $ENV{CXX};
-	print "    BUILDFILE = ",$ENV{BUILDFILE},"\n" if $ENV{BUILDFILE};
-	print "    $local_config_envname = ",$ENV{$local_config_envname},"\n"
-	    if $ENV{$local_config_envname};
+	foreach (sort keys %{$config{perlenv}}) {
+	    print "    $_ = $config{perlenv}->{$_}\n";
+	}
     } else {
 	die "Insufficient data to reconfigure, please do a normal configuration\n";
     }
@@ -280,13 +267,13 @@ foreach (sort glob($pattern)) {
     &read_config($_);
 }
 
-if (defined $ENV{$local_config_envname}) {
+if (defined env($local_config_envname)) {
     if ($^O eq 'VMS') {
         # VMS environment variables are logical names,
         # which can be used as is
         $pattern = $local_config_envname . ':' . '*.conf';
     } else {
-        $pattern = catfile($ENV{$local_config_envname}, '*.conf');
+        $pattern = catfile(env($local_config_envname), '*.conf');
     }
 
     foreach (sort glob($pattern)) {
@@ -982,7 +969,7 @@ $target{dso_extension}=$target{shared_extension_simple};
     if ($config{target} =~ /^(?:Cygwin|mingw)/);
 
 
-$config{cross_compile_prefix} = $ENV{'CROSS_COMPILE'}
+$config{cross_compile_prefix} = env('CROSS_COMPILE')
     if $config{cross_compile_prefix} eq "";
 
 # Allow overriding the names of some tools.  USE WITH CARE
@@ -990,19 +977,19 @@ $config{cross_compile_prefix} = $ENV{'CROSS_COMPILE'}
 # the default string.
 $config{perl} =    ($^O ne "VMS" ? $^X : "perl");
 $config{hashbangperl} =
-    $ENV{'HASHBANGPERL'}           || $ENV{'PERL'}     || "/usr/bin/env perl";
-$target{cc} =      $ENV{'CC'}      || $target{cc}      || "cc";
-$target{cxx} =     $ENV{'CXX'}     || $target{cxx}     || "c++";
-$target{ranlib} =  $ENV{'RANLIB'}  || $target{ranlib}  ||
+    env('HASHBANGPERL')           || env('PERL')      || "/usr/bin/env perl";
+$target{cc} =      env('CC')      || $target{cc}      || "cc";
+$target{cxx} =     env('CXX')     || $target{cxx}     || "c++";
+$target{ranlib} =  env('RANLIB')  || $target{ranlib}  ||
                    (which("$config{cross_compile_prefix}ranlib") ?
                           "\$(CROSS_COMPILE)ranlib" : "true");
-$target{ar} =      $ENV{'AR'}      || $target{ar}      || "ar";
-$target{nm} =      $ENV{'NM'}      || $target{nm}      || "nm";
+$target{ar} =      env('AR')      || $target{ar}      || "ar";
+$target{nm} =      env('NM')      || $target{nm}      || "nm";
 $target{rc} =
-    $ENV{'RC'}  || $ENV{'WINDRES'} || $target{rc}      || "windres";
+    env('RC')  || env('WINDRES')  || $target{rc}      || "windres";
 
 # Allow overriding the build file name
-$target{build_file} = $ENV{BUILDFILE} || $target{build_file} || "Makefile";
+$target{build_file} = env('BUILDFILE') || $target{build_file} || "Makefile";
 
 # Cache information necessary for reconfiguration
 $config{cc} = $target{cc};
@@ -1418,7 +1405,7 @@ if ($builder eq "unified") {
     my @build_file_templates = ();
 
     # First, look in the user provided directory, if given
-    if (defined $ENV{$local_config_envname}) {
+    if (defined env($local_config_envname)) {
 	@build_file_templates =
 	    map {
 		if ($^O eq 'VMS') {
@@ -1426,7 +1413,7 @@ if ($builder eq "unified") {
 		    # which can be used as is
 		    $local_config_envname . ':' . $_;
 		} else {
-		    catfile($ENV{$local_config_envname}, $_);
+		    catfile(env($local_config_envname), $_);
 		}
 	    }
 	    @build_file_template_names;
@@ -2009,6 +1996,22 @@ foreach (sort keys %config) {
 	print OUT "  ", $_, " => [ ", join(", ",
 					   map { quotify("perl", $_) }
 					   @{$config{$_}}), " ],\n";
+    } elsif (ref($config{$_}) eq "HASH") {
+	print OUT "  ", $_, " => {";
+        if (scalar keys %{$config{$_}} > 0) {
+            print OUT "\n";
+            foreach my $key (sort keys %{$config{$_}}) {
+                print OUT "      ",
+                    join(" => ",
+                         quotify("perl", $key),
+                         defined $config{$_}->{$key}
+                             ? quotify("perl", $config{$_}->{$key})
+                             : "undef");
+                print OUT ",\n";
+            }
+            print OUT "  ";
+        }
+        print OUT "},\n";
     } else {
 	print OUT "  ", $_, " => ", quotify("perl", $config{$_}), ",\n"
     }
@@ -2522,6 +2525,15 @@ sub which
     }
 }
 
+sub env
+{
+    my $name = shift;
+
+    return $config{perlenv}->{$name} if exists $config{perlenv}->{$name};
+    $config{perlenv}->{$name} = $ENV{$name};
+    return $config{perlenv}->{$name};
+}
+
 # Configuration printer ##############################################
 
 sub print_table_entry