Make it possible for older masm to compile sse2 modules.

PR: 1592

crypto/perlasm/x86ms.pl

@@ -339,8 +339,17 @@ EOF
 sub main'file_end
 	{
 	# try to detect if SSE2 or MMX extensions were used...
-	if (grep {/\b[x]?mm[0-7]\b,/i} @out) {
-		grep {s/\.[3-7]86/\.686\n\t\.XMM/} @out;
+	my $xmmheader=<<___;
+.686
+.XMM
+IF \@Version LT 800
+XMMWORD STRUCT 16
+	DQ  2 dup (?)
+XMMWORD ENDS
+ENDIF
+___
+	if (grep {/\b[x]?mm[0-7]\b/i} @out) {
+		grep {s/\.[3-7]86/$xmmheader/} @out;
 		}
 	push(@out,"_TEXT\$	ENDS\n");
 	push(@out,"END\n");