[glib] Use env for gdbus-codegen's script

[Emmanuele Bassi <ebassi src gnome org>]

commit 683809d5f751575775d12917581eb7b9a2acf0f5
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Fri Jul 14 22:05:01 2017 +0100

    Use env for gdbus-codegen's script
    
    This allows us to build with Python 3 without using an absolute path.

 gio/gdbus-2.0/codegen/gdbus-codegen.in |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gio/gdbus-2.0/codegen/gdbus-codegen.in b/gio/gdbus-2.0/codegen/gdbus-codegen.in
index 4558aa3..8050981 100644
--- a/gio/gdbus-2.0/codegen/gdbus-codegen.in
+++ b/gio/gdbus-2.0/codegen/gdbus-codegen.in
@@ -1,4 +1,4 @@
-#!@PYTHON@
+#!/usr/bin/env @PYTHON@
 
 # GDBus - GLib D-Bus Library
 #