Get glib to compile with gcc-6.1

[glennpj]

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.

[glennpj]

It looks like there may be a problem with the travis check itself. The failure that I see, for only the python-2.6 test is:

======================================================================
ERROR: test_svn_mirror (spack.test.mirror.MirrorTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/build/LLNL/spack/lib/spack/spack/test/mirror.py", line 129, in test_svn_mirror
    self.check_mirror()
  File "/home/travis/build/LLNL/spack/lib/spack/spack/test/mirror.py", line 108, in check_mirror
    pkg.do_stage(mirror_only=True)
  File "/home/travis/build/LLNL/spack/lib/spack/spack/package.py", line 744, in do_stage
    self.stage.expand_archive()
  File "/home/travis/build/LLNL/spack/lib/spack/spack/util/pattern.py", line 74, in getter
    getattr(item, self.name)(*args, **kwargs)
  File "/home/travis/build/LLNL/spack/lib/spack/spack/stage.py", line 343, in expand_archive
    self.fetcher.expand()
  File "/home/travis/build/LLNL/spack/lib/spack/spack/fetch_strategy.py", line 72, in wrapper
    return fun(self, *args, **kwargs)
  File "/home/travis/build/LLNL/spack/lib/spack/spack/fetch_strategy.py", line 282, in expand
    decompress(self.archive_file)
  File "/home/travis/build/LLNL/spack/lib/spack/spack/util/executable.py", line 166, in __call__
    proc.returncode, cmd_line)
ProcessError: Command exited with status 2:
    '/bin/tar' '-xf' '/home/travis/build/LLNL/spack/var/spack/stage/svn-test-svn-pxzjmse7a3w5w4zquwtkxnoczu2yh26j/svn-test-svn.tar.gz'

----------------------------------------------------------------------
Ran 5 tests in 13.369s

FAILED (errors=1)
spack.test.modules
�[1;34m==>�[0m Running test: modules
.....

That seems unrelated to any changes made in this PR.

[mathstuf]

ProcessError: Command exited with status 2:

Hmm, yeah, seems that something went south inside of tar (2 Fatal error. This means that some fatal, unrecoverable error occurred.). Corrupt file?

[glennpj]

@mathstuf I am not seeing that happen here.

[mathstuf]

Was analyzing the error output from the tests :) . I agree it is likely not something that's an issue with the branch.

[glennpj]

@mathstuf Sorry, I had forgotten about the test errors. The email updates do not provide enough (any) context.

Thanks.

[mathstuf]

Ah, missed that the error had occurred 2+ weeks ago :) . Yep, would have quoted more if I had realized that.

[mathstuf]

Sigh. This works for GCC, but clang is obstinate and still errors out on it :( .