CGrammar: Fix shebangs to use env to detect perl location

PBot/VERSION.pm

@@ -13,7 +13,7 @@ use warnings;
 # These are set automatically by the build/commit script
 use constant {
   BUILD_NAME     => "PBot",
-  BUILD_REVISION => 706,
+  BUILD_REVISION => 707,
   BUILD_DATE     => "2014-07-04",
 };
 

modules/c2english.pl

@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 use warnings;
 use strict;

modules/c2english/c2eng.pl

@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 use strict;
 use warnings;