fix perl shebang

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
diff --git a/ms/cmp.pl b/ms/cmp.pl
index e6f8368..31d7e1e 100644
--- a/ms/cmp.pl
+++ b/ms/cmp.pl
@@ -1,4 +1,4 @@
-#!/usr/local/bin/perl
+#!/usr/bin/env perl
 
 ($#ARGV == 1) || die "usage: cmp.pl <file1> <file2>\n";