Allow setting RCFLAGS as Configure option or environment variable

Reviewed-by: NTim Hudson <tjh@openssl.org>
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8803)

(cherry picked from commit 0c4e984de28b1477e002766b2751576f5c6c47d6)

Configure

@@ -562,7 +562,7 @@ my %user = (
     PERL        => env('PERL') || ($^O ne "VMS" ? $^X : "perl"),
     RANLIB      => env('RANLIB'),
     RC          => env('RC') || env('WINDRES'),
-    RCFLAGS     => [],
+    RCFLAGS     => [ env('RCFLAGS') || () ],
     RM          => undef,
    );
 # Info about what "make variables" may be prefixed with the cross compiler
@@ -579,6 +579,7 @@ my %useradd = (
     CXXFLAGS    => [],
     LDFLAGS     => [],
     LDLIBS      => [],
+    RCFLAGS     => [],
    );
 
 my %user_synonyms = (