asan/msan/tsan: move _exit interceptor to common interceptors



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@191903 91177308-0d34-0410-b5e6-96231b3b80d8
asan/msan: fix "unused function 'OnExit'" warning


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@191904 91177308-0d34-0410-b5e6-96231b3b80d8