MAINT: Remove compile flag that is no longer needed.

setup.py

@@ -290,7 +290,7 @@ def run(self):
 class CheckingBuildExt(build_ext):
     """
     Subclass build_ext to get clearer report if Cython is necessary.
-    Also, add some platform based compiler flags.
+
     """
 
     def check_cython_extensions(self, extensions):
@@ -304,27 +304,8 @@ def check_cython_extensions(self, extensions):
 
     def build_extensions(self):
         self.check_cython_extensions(self.extensions)
-        self.add_gnu_inline_flag(self.extensions)
         build_ext.build_extensions(self)
 
-    def add_gnu_inline_flag(self, extensions):
-        '''
-        Add CFLAGS `-fgnu89-inline` for clang on FreeBSD 10+
-        '''
-        if not platform.system() == 'FreeBSD':
-            return
-
-        try:
-            bsd_release = float(platform.release().split('-')[0])
-        except ValueError:  # unknow freebsd version
-            return
-
-        if bsd_release < 10:  # 9 or earlier still using gcc42
-            return
-
-        for ext in extensions:
-            ext.extra_compile_args += ['-fgnu89-inline']
-
 
 class CythonCommand(build_ext):
     """Custom distutils command subclassed from Cython.Distutils.build_ext