Fix mac build.

Author: dvander

AMBuildScript

@@ -227,6 +227,8 @@ class AMXXConfig(object):
         cxx.cflags += ['-Wno-unused-result', '-Wno-error=sign-compare']
     if have_clang:
       cxx.cxxflags += ['-Wno-implicit-exception-spec-mismatch']
+      if cxx.version >= 'apple-clang-10.0':
+        cxx.cxxflags += ['-Wno-inconsistent-missing-override']
       if cxx.version >= 'apple-clang-5.1' or cxx.version >= 'clang-3.4':
         cxx.cxxflags += ['-Wno-deprecated-register']
       else: