Translate .L directives inside .byte too.

Win64 unwind tables place distances from the start of a function in
byte-wide values.

Change-Id: Ie2aad7f6f5b702a60933bd52d872a83cba4e73a9
Reviewed-on: https://boringssl-review.googlesource.com/c/33784
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <alangley@gmail.com>

crypto/perlasm/x86_64-xlate.pl

@@ -742,7 +742,7 @@ my %globals;
 				    }
 				    last;
 				  };
-		/\.rva|\.long|\.quad/
+		/\.rva|\.long|\.quad|\.byte/
 			    && do { $$line =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei;
 				    $$line =~ s/\.L/$decor/g;
 				    last;