Fix build, fix epollex detection

CMakeLists.txt

Makefile

binding.gyp

build.yaml

config.m4

gRPC-Core.podspec

grpc.gemspec

package.xml

src/core/lib/iomgr/ev_epollex_linux.c

src/python/grpcio/grpc_core_dependencies.py

tools/doxygen/Doxyfile.c++.internal

tools/doxygen/Doxyfile.core.internal

tools/run_tests/generated/sources_and_headers.json

vsprojects/vcxproj/grpc++/grpc++.vcxproj

vsprojects/vcxproj/grpc++/grpc++.vcxproj.filters

vsprojects/vcxproj/grpc++_unsecure/grpc++_unsecure.vcxproj

...s/vcxproj/grpc++_unsecure/grpc++_unsecure.vcxproj.filters

vsprojects/vcxproj/grpc/grpc.vcxproj

vsprojects/vcxproj/grpc/grpc.vcxproj.filters

vsprojects/vcxproj/grpc_test_util/grpc_test_util.vcxproj