Include CompilerRTCompile in fuzzer tests explicitly. Otherwise, when
building only libFuzzer, CMake fails due to:
CMake Error at cmake/Modules/AddCompilerRT.cmake:395 (sanitizer_test_compile):
Unknown CMake command "sanitizer_test_compile".
Call Stack (most recent call first):
lib/fuzzer/tests/CMakeLists.txt:53 (generate_compiler_rt_tests)
Differential Revision: https://reviews.llvm.org/D55378
llvm-svn: 348524