{chacha|poly1305}/asm/*-x64.pl: harmonize clang version detection.

Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6499)

crypto/chacha/asm/chacha-x86.pl

@@ -62,7 +62,7 @@ $ymm=1 if ($xmm && !$ymm && $ARGV[0] eq "win32" &&
 		$1>=10);	# first version supporting AVX
 
 $ymm=1 if ($xmm && !$ymm &&
-		`$ENV{CC} -v 2>&1` =~ /(^clang version|based on LLVM) ([3-9]\.[0-9]+)/ &&
+		`$ENV{CC} -v 2>&1` =~ /((?:^clang|LLVM) version|based on LLVM) ([3-9]\.[0-9]+)/ &&
 		$2>=3.0);	# first version supporting AVX
 
 $a="eax";

crypto/poly1305/asm/poly1305-x86.pl

@@ -71,7 +71,7 @@ if ($sse2) {
 	$avx = ($1>=2.09) + ($1>=2.10);
 	}
 
-	if (!$avx && `$ENV{CC} -v 2>&1` =~ /(^clang version|based on LLVM) ([3-9]\.[0-9]+)/) {
+	if (!$avx && `$ENV{CC} -v 2>&1` =~ /((?:^clang|LLVM) version|based on LLVM) ([3-9]\.[0-9]+)/) {
 		$avx = ($2>=3.0) + ($2>3.0);
 	}
 }