Fix compilation when using MASM on x86

The generated asm code from x86cpuid.pl contains CMOVE instructions
which are only available on i686 and later CPUs.
Reviewed-by: NAndy Polyakov <appro@openssl.org>
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1459)

crypto/perlasm/x86masm.pl

@@ -89,7 +89,7 @@ TITLE	$_[0].asm
 IF \@Version LT 800
 ECHO MASM version 8.00 or later is strongly recommended.
 ENDIF
-.486
+.686
 .MODEL	FLAT
 OPTION	DOTNAME
 IF \@Version LT 800