remove -Werror from CFLAGS

In issue #335, @mvduin noted that it is a poor idea to have compilation fail on warnings because a newer compiler version may add new warnings and as a result break compilation.

Author: pdp7

setup.py

@@ -21,7 +21,7 @@
 else:
     kernel41 = None
 
-CFLAGS = ['-Wall', '-Werror', '-Wextra', '-Wno-missing-field-initializers', '-Wno-strict-aliasing' ]
+CFLAGS = ['-Wall', '-Wextra', '-Wno-missing-field-initializers', '-Wno-strict-aliasing' ]
 
 classifiers = ['Development Status :: 3 - Alpha',
                'Operating System :: POSIX :: Linux',