Make util/mkrc.pl location agnostic and adapt Makefile.shared

With this, Cygwin and Mingw builds stand a much better chance to be
able to build outside of the source tree with the unified build.

Reviewed-by: Rich Salz <rsalz@openssl.org>

Makefile.shared

@@ -308,7 +308,7 @@ link_a.cygwin:
 		base=; [ $(LIBNAME) = "crypto" ] && base=-Wl,--image-base,0x63000000; \
 	fi; \
 	dll_name=$$SHLIB$$SHLIB_SOVER$$SHLIB_SUFFIX; \
-	$(PERL) util/mkrc.pl $$dll_name | \
+	$(PERL) $(SRCDIR)/util/mkrc.pl $$dll_name | \
 		$(CROSS_COMPILE)windres $(SHARED_RCFLAGS) -o rc.o; \
 	extras="$$extras rc.o"; \
 	ALLSYMSFLAGS='-Wl,--whole-archive'; \

util/mkrc.pl

@@ -1,6 +1,13 @@
 #!/bin/env perl
 #
-open FD,"include/openssl/opensslv.h";
+
+use lib ".";
+use configdata;
+use File::Spec::Functions;
+
+my $versionfile = catfile($config{sourcedir},"include/openssl/opensslv.h");
+
+open FD, $versionfile or die "Couldn't open include/openssl/opensslv.h: $!\n";
 while(<FD>) {
     if (/OPENSSL_VERSION_NUMBER\s+(0x[0-9a-f]+)/i) {
 	$ver = hex($1);