Configure: allow to enable afalgeng if target does not start with Linux

The Debian build system uses a `debian' target which sets CFLAGS and
then we have for instance debian-amd64 which inherits from
linux-x86_64 and debian [0]. So far so good.

Unless there are different suggestions how to do this, I would keep it.
However since the target name does not start with `linux', the build
system does not enable the afalg engine. So in order to get enabled, I
added a
	`enable           => [ "afalgeng" ],'
to the generic linux config which sets it explicit (as suggested by
Richard Levitte). Having this set, we can check for it instead matching
the target name.

[0] https://sources.debian.org/src/openssl/1.1.0g-2/Configurations/20-debian.conf/Signed-off-by: NSebastian Andrzej Siewior <sebastian@breakpoint.cc>
Reviewed-by: NMatt Caswell <matt@openssl.org>
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5169)

Configurations/10-main.conf

@@ -679,6 +679,7 @@ my %targets = (
         shared_cflag     => "-fPIC",
         shared_ldflag    => "-Wl,-znodelete",
         shared_extension => ".so.\$(SHLIB_VERSION_NUMBER)",
+        enable           => [ "afalgeng" ],
     },
     "linux-generic64" => {
         inherit_from     => [ "linux-generic32" ],

Configure

@@ -1518,7 +1518,7 @@ unless ($disabled{"crypto-mdebug-backtrace"})
 
 unless ($disabled{afalgeng}) {
     $config{afalgeng}="";
-    if ($target =~ m/^linux/) {
+    if (grep { $_ eq 'afalgeng' } @{$target{enable}}) {
         my $minver = 4*10000 + 1*100 + 0;
         if ($config{CROSS_COMPILE} eq "") {
             my $verstr = `uname -r`;