Backport 2.1: Use "#!/usr/bin/env perl" as shebang line.
diff --git a/scripts/rename.pl b/scripts/rename.pl
index c169078..22a86cc 100755
--- a/scripts/rename.pl
+++ b/scripts/rename.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 # rename identifiers (functions, types, enum constant, etc)
 # on upgrades of major version according to a list