use env for perl in this script

diff --git a/tools/smpi/generate_smpi_defines.pl b/tools/smpi/generate_smpi_defines.pl
index 1306f45..be61448 100755 (executable)
--- a/tools/smpi/generate_smpi_defines.pl
+++ b/tools/smpi/generate_smpi_defines.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 # Copyright 2016 Vincent Danjean <vincent.danjean@inria.fr>
 # 
 # Call this script like this: