fail build in CI if speedups do not build correctly

.travis/run.sh

@@ -9,8 +9,7 @@ if [[ $TRAVIS_OS_NAME == 'osx' ]]; then
     hash -r
     eval "$(pyenv init -)"
 fi
-
-python setup.py build_ext -i
+REQUIRE_SPEEDUPS=1 python setup.py build_ext -i
 python -m compileall -f .
 python setup.py test
 

appveyor/run_with_env.cmd

@@ -31,6 +31,7 @@
 :: case, I don't know why.
 @ECHO OFF
 
+SET REQUIRE_SPEEDUPS=Y
 SET COMMAND_TO_RUN=%*
 SET WIN_SDK_ROOT=C:\Program Files\Microsoft SDKs\Windows
 SET WIN_WDK=c:\Program Files (x86)\Windows Kits\10\Include\wdf

setup.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 from __future__ import with_statement
 
+import os
 import sys
 try:
     from setuptools import setup, Extension, Command
@@ -112,6 +113,8 @@ def run_setup(with_binary):
 try:
     run_setup(not IS_PYPY)
 except BuildFailed:
+    if os.environ.get('REQUIRE_SPEEDUPS'):
+        raise
     BUILD_EXT_WARNING = ("WARNING: The C extension could not be compiled, "
                          "speedups are not enabled.")
     print('*' * 75)