Bug 1368623 - use PERL env variabel in certdata.py, r=ttaubert

--HG--
extra : transplant_source : %C2%88lyJ%D4d%A4%B8%1CJ%FEu.q%02%E9%3E_%CE

lib/ckfw/builtins/certdata.py

@@ -11,7 +11,8 @@
 def main():
     args = [os.path.realpath(x) for x in sys.argv[1:]]
     script = os.path.dirname(os.path.abspath(__file__))+'/certdata.perl'
-    subprocess.check_call(['perl', script] + args, env=os.environ)
+    subprocess.check_call([os.environ.get('PERL', 'perl'), script] + args,
+                          env=os.environ)
 
 if __name__ == '__main__':
     main()