Fixed wrong usage of global var

BUILD

Makefile

build.yaml

include/grpc++/impl/grpc_library.h

src/cpp/client/channel.cc

src/cpp/client/credentials.cc

src/cpp/client/secure_credentials.cc

src/cpp/common/alarm.cc

src/cpp/common/completion_queue.cc

src/cpp/common/grpc_library_initializer.cc

src/cpp/server/server.cc

tools/doxygen/Doxyfile.c++.internal

tools/run_tests/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