Remove unused files

BUILD

Makefile

binding.gyp

build.yaml

config.m4

gRPC.podspec

grpc.gemspec

package.xml

src/core/lib/iomgr/ctiller_ev_epoll_linux.c

src/core/lib/iomgr/ev_epoll_linux.c

src/core/lib/iomgr/ev_epoll_posix.c

src/core/lib/iomgr/ev_epoll_posix.h

src/python/grpcio/grpc_core_dependencies.py

test/core/network_benchmarks/epoll_test.c

test/core/network_benchmarks/low_level_ping_pong.c

tools/doxygen/Doxyfile.core.internal

tools/run_tests/sources_and_headers.json

tools/run_tests/tests.json

vsprojects/vcxproj/grpc/grpc.vcxproj

vsprojects/vcxproj/grpc/grpc.vcxproj.filters