Get glib to compile with gcc-6.1

This commit adds a patch to fix the case where gcc-6.1 emits an error
for string format literal that was a warning in previous versions of
gcc. The patch reference is
https://bugzilla.gnome.org/show_bug.cgi?id=761550

Also ran the package file through autopep8.

var/spack/repos/builtin/packages/glib/package.py

@@ -25,20 +25,23 @@
 from spack import *
 import sys
 
+
 class Glib(Package):
     """The GLib package contains a low-level libraries useful for
        providing data structure handling for C, portability wrappers
        and interfaces for such runtime functionality as an event loop,
        threads, dynamic loading and an object system."""
     homepage = "https://developer.gnome.org/glib/"
-    url      = "http://ftp.gnome.org/pub/gnome/sources/glib/2.42/glib-2.42.1.tar.xz"
+    url = "http://ftp.gnome.org/pub/gnome/sources/glib/2.42/glib-2.42.1.tar.xz"
 
     version('2.42.1', '89c4119e50e767d3532158605ee9121a')
 
     depends_on("libffi")
     depends_on("zlib")
     depends_on("pkg-config")
-    depends_on('gettext', sys.platform=='darwin')
+    depends_on('gettext', sys.platform == 'darwin')
+
+    patch('g_date_strftime.patch')
 
     def install(self, spec, prefix):
         configure("--prefix=%s" % prefix)