Lowercase configuration arguments on VMS

Depending on user preferences, Configure might get something like
--PREFIX=blah just as well as --prefix=blah, or "SHARED" just as well
as "shared".  On VMS, let's therefore lowercase at least the portion
of the argument before a possible equal sign.

For good measure, we lowercase the arguments to be checked in
config.com as well.  The original argument is sent on to Configure,
however.

Reviewed-by: Andy Polyakov <appro@openssl.org>
diff --git a/Configure b/Configure
index 1077371..9a4a9a9 100755
--- a/Configure
+++ b/Configure
@@ -501,6 +501,13 @@
 my %unsupported_options = ();
 foreach (@argvcopy)
 	{
+	# VMS is a case insensitive environment, and depending on settings
+	# out of our control, we may receive options uppercased.  Let's
+	# downcase at least the part before any equal sign.
+	if ($^O eq "VMS")
+		{
+		s/^([^=]*)/lc($1)/e;
+		}
 	s /^-no-/no-/; # some people just can't read the instructions
 
 	# rewrite some options in "enable-..." form