[WIP][compiler-rt] Build fuzzer tests

clang/cmake/caches/Fuchsia-stage2.cmake

if(LINUX_${target}_SYSROOT)
     set(RUNTIMES_${target}_CMAKE_C_FLAGS "--target=${target}" CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_CXX_FLAGS "--target=${target}" CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_ASM_FLAGS "--target=${target}" CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_SYSROOT ${LINUX_${target}_SYSROOT} CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_SHARED_LINKER_FLAGS "-fuse-ld=lld" CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_MODULE_LINKER_FLAGS "-fuse-ld=lld" CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_EXE_LINKER_FLAGS "-fuse-ld=lld" CACHE STRING "")
     set(RUNTIMES_${target}_COMPILER_RT_USE_BUILTINS_LIBRARY ON CACHE BOOL "")
+    set(RUNTIMES_${target}_COMPILER_RT_CAN_EXECUTE_TESTS ON CACHE BOOL "")
     set(RUNTIMES_${target}_LIBUNWIND_ENABLE_SHARED OFF CACHE BOOL "")
     set(RUNTIMES_${target}_LIBUNWIND_USE_COMPILER_RT ON CACHE BOOL "")
     set(RUNTIMES_${target}_LIBUNWIND_INSTALL_LIBRARY OFF CACHE BOOL "")
     set(RUNTIMES_${target}_LIBCXXABI_USE_COMPILER_RT ON CACHE BOOL "")
     set(RUNTIMES_${target}_LIBCXXABI_ENABLE_SHARED OFF CACHE BOOL "")
     set(RUNTIMES_${target}_LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
     set(RUNTIMES_${target}_LIBCXXABI_ENABLE_STATIC_UNWINDER ON CACHE BOOL "")
     set(RUNTIMES_${target}_LIBCXXABI_INSTALL_LIBRARY OFF CACHE BOOL "")

compiler-rt/cmake/Modules/AddCompilerRT.cmake

function(add_compiler_rt_test test_suite test_name arch)
   endif()
   if(NOT COMPILER_RT_STANDALONE_BUILD AND COMPILER_RT_HAS_LLD AND "lld" IN_LIST LLVM_ENABLE_PROJECTS)
     # CMAKE_EXE_LINKER_FLAGS may contain -fuse=lld
     # FIXME: -DLLVM_ENABLE_LLD=ON and -DLLVM_ENABLE_PROJECTS without lld case.
     list(APPEND TEST_DEPS lld)
   endif()
   add_custom_command(
     OUTPUT "${output_bin}"
-    COMMAND ${COMPILER_RT_TEST_COMPILER} ${TEST_OBJECTS} -o "${output_bin}"
+    COMMAND ${COMPILER_RT_TEST_CXX_COMPILER} ${TEST_OBJECTS} -o "${output_bin}"
             ${TEST_LINK_FLAGS}
     DEPENDS ${TEST_DEPS}
     )
   add_custom_target(T${test_name} DEPENDS "${output_bin}")
   set_target_properties(T${test_name} PROPERTIES FOLDER "Compiler-RT Tests")
 
   # Make the test suite depend on the binary.
   add_dependencies(${test_suite} T${test_name})

compiler-rt/lib/fuzzer/tests/CMakeLists.txt

if (APPLE)
     list(APPEND LIBFUZZER_UNITTEST_LINK_FLAGS -isysroot ${DARWIN_osx_SYSROOT})
   endif()
   list(APPEND LIBFUZZER_UNITTEST_LINK_FLAGS -lpthread)
 endif()
 
 if(CMAKE_SYSTEM_NAME STREQUAL "Linux" AND
    COMPILER_RT_LIBCXX_PATH AND
    COMPILER_RT_LIBCXXABI_PATH)
-  list(APPEND LIBFUZZER_UNITTEST_CFLAGS -nostdinc++)
+  list(APPEND LIBFUZZER_UNITTEST_CFLAGS -nostdinc++ -fno-exceptions)
+  list(APPEND LIBFUZZER_UNITTEST_LINK_FLAGS -nostdlib++ -fno-exceptions)
 endif()
 
 if ("-fvisibility=hidden" IN_LIST LIBFUZZER_CFLAGS)
   # Match visibility settings.
   list(APPEND LIBFUZZER_UNITTEST_CFLAGS "-fvisibility=hidden")
 endif()
 
 if(COMPILER_RT_DEFAULT_TARGET_ARCH IN_LIST FUZZER_SUPPORTED_ARCH)