Description of problem:

How reproducible:

Steps to Reproduce:
1. yum install python-pygit2-0.21.4-2.el7.x86_64
2. python -c "import pygit2"

Actual results:
unable to execute gcc: No such file or directory
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib64/python2.7/site-packages/pygit2/__init__.py", line 35, in <module>
    from .blame import Blame, BlameHunk
  File "/usr/lib64/python2.7/site-packages/pygit2/blame.py", line 32, in <module>
    from .errors import check_error
  File "/usr/lib64/python2.7/site-packages/pygit2/errors.py", line 29, in <module>
    from .ffi import ffi, C
  File "/usr/lib64/python2.7/site-packages/pygit2/ffi.py", line 35, in <module>
    ffi, C = get_ffi()
  File "/usr/lib64/python2.7/site-packages/pygit2/_utils.py", line 101, in get_ffi
    include_dirs=[libgit2_include], library_dirs=[libgit2_lib])
  File "/usr/lib64/python2.7/site-packages/cffi/api.py", line 450, in verify
    lib = self.verifier.load_library()
  File "/usr/lib64/python2.7/site-packages/cffi/verifier.py", line 113, in load_library
    self._compile_module()
  File "/usr/lib64/python2.7/site-packages/cffi/verifier.py", line 210, in _compile_module
    outputfilename = ffiplatform.compile(tmpdir, self.get_extension())
  File "/usr/lib64/python2.7/site-packages/cffi/ffiplatform.py", line 29, in compile
    outputfilename = _build(tmpdir, ext, compiler_verbose)
  File "/usr/lib64/python2.7/site-packages/cffi/ffiplatform.py", line 62, in _build
    raise VerificationError('%s: %s' % (e.__class__.__name__, e))
cffi.ffiplatform.VerificationError: CompileError: command 'gcc' failed with exit status 1

Expected results:
No errors