[CMake] Passthrough CFLAGS when checking the compiler-rt path

[phosek]

Summary

This is needed when cross-compiling for a different target since
CFLAGS may contain additional flags like -resource-dir which
change the location in which compiler-rt builtins are found.

[beanz]

LGTM

compiler-rt/trunk/cmake/Modules/HandleCompilerRT.cmake

 function(find_compiler_rt_library name variable)
   set(CLANG_COMMAND ${CMAKE_CXX_COMPILER} ${SANITIZER_COMMON_CFLAGS}
       "--rtlib=compiler-rt" "--print-libgcc-file-name")
   if (CMAKE_CXX_COMPILER_ID MATCHES Clang AND CMAKE_CXX_COMPILER_TARGET)
     list(APPEND CLANG_COMMAND "--target=${CMAKE_CXX_COMPILER_TARGET}")
   endif()
+  get_property(SANITIZER_CXX_FLAGS CACHE CMAKE_CXX_FLAGS PROPERTY VALUE)
+  string(REPLACE " " ";" SANITIZER_CXX_FLAGS "${SANITIZER_CXX_FLAGS}")
+  list(APPEND CLANG_COMMAND ${SANITIZER_CXX_FLAGS})
   execute_process(
       COMMAND ${CLANG_COMMAND}
       RESULT_VARIABLE HAD_ERROR
       OUTPUT_VARIABLE LIBRARY_FILE
   )
   string(STRIP "${LIBRARY_FILE}" LIBRARY_FILE)
   string(REPLACE "builtins" "${name}" LIBRARY_FILE "${LIBRARY_FILE}")
   if (NOT HAD_ERROR AND EXISTS "${LIBRARY_FILE}")
     message(STATUS "Found compiler-rt ${name} library: ${LIBRARY_FILE}")
     set(${variable} "${LIBRARY_FILE}" PARENT_SCOPE)
   else()
     message(STATUS "Failed to find compiler-rt ${name} library")
   endif()
 endfunction()

libcxx/trunk/cmake/Modules/HandleCompilerRT.cmake

 function(find_compiler_rt_library name dest)
   if (NOT DEFINED LIBCXX_COMPILE_FLAGS)
     message(FATAL_ERROR "LIBCXX_COMPILE_FLAGS must be defined when using this function")
   endif()
   set(dest "" PARENT_SCOPE)
   set(CLANG_COMMAND ${CMAKE_CXX_COMPILER} ${LIBCXX_COMPILE_FLAGS}
       "--rtlib=compiler-rt" "--print-libgcc-file-name")
   if (CMAKE_CXX_COMPILER_ID MATCHES Clang AND CMAKE_CXX_COMPILER_TARGET)
     list(APPEND CLANG_COMMAND "--target=${CMAKE_CXX_COMPILER_TARGET}")
   endif()
+  get_property(LIBCXX_CXX_FLAGS CACHE CMAKE_CXX_FLAGS PROPERTY VALUE)
+  string(REPLACE " " ";" LIBCXX_CXX_FLAGS "${LIBCXX_CXX_FLAGS}")
+  list(APPEND CLANG_COMMAND ${LIBCXX_CXX_FLAGS})
   execute_process(
       COMMAND ${CLANG_COMMAND}
       RESULT_VARIABLE HAD_ERROR
       OUTPUT_VARIABLE LIBRARY_FILE
   )
   string(STRIP "${LIBRARY_FILE}" LIBRARY_FILE)
   file(TO_CMAKE_PATH "${LIBRARY_FILE}" LIBRARY_FILE)
   string(REPLACE "builtins" "${name}" LIBRARY_FILE "${LIBRARY_FILE}")

libcxxabi/trunk/cmake/Modules/HandleCompilerRT.cmake

 function(find_compiler_rt_library name dest)
   if (NOT DEFINED LIBCXXABI_COMPILE_FLAGS)
     message(FATAL_ERROR "LIBCXXABI_COMPILE_FLAGS must be defined when using this function")
   endif()
   set(dest "" PARENT_SCOPE)
   set(CLANG_COMMAND ${CMAKE_CXX_COMPILER} ${LIBCXXABI_COMPILE_FLAGS}
       "--rtlib=compiler-rt" "--print-libgcc-file-name")
   if (CMAKE_CXX_COMPILER_ID MATCHES Clang AND CMAKE_CXX_COMPILER_TARGET)
     list(APPEND CLANG_COMMAND "--target=${CMAKE_CXX_COMPILER_TARGET}")
   endif()
+  get_property(LIBCXXABI_CXX_FLAGS CACHE CMAKE_CXX_FLAGS PROPERTY VALUE)
+  string(REPLACE " " ";" LIBCXXABI_CXX_FLAGS "${LIBCXXABI_CXX_FLAGS}")
+  list(APPEND CLANG_COMMAND ${LIBCXXABI_CXX_FLAGS})
   execute_process(
       COMMAND ${CLANG_COMMAND}
       RESULT_VARIABLE HAD_ERROR
       OUTPUT_VARIABLE LIBRARY_FILE
   )
   string(STRIP "${LIBRARY_FILE}" LIBRARY_FILE)
   file(TO_CMAKE_PATH "${LIBRARY_FILE}" LIBRARY_FILE)
   string(REPLACE "builtins" "${name}" LIBRARY_FILE "${LIBRARY_FILE}")

libunwind/trunk/cmake/Modules/HandleCompilerRT.cmake

 function(find_compiler_rt_library name dest)
   if (NOT DEFINED LIBUNWIND_COMPILE_FLAGS)
     message(FATAL_ERROR "LIBUNWIND_COMPILE_FLAGS must be defined when using this function")
   endif()
   set(dest "" PARENT_SCOPE)
   set(CLANG_COMMAND ${CMAKE_CXX_COMPILER} ${LIBUNWIND_COMPILE_FLAGS}
       "--rtlib=compiler-rt" "--print-libgcc-file-name")
   if (CMAKE_CXX_COMPILER_ID MATCHES Clang AND CMAKE_CXX_COMPILER_TARGET)
     list(APPEND CLANG_COMMAND "--target=${CMAKE_CXX_COMPILER_TARGET}")
   endif()
+  get_property(LIBUNWIND_CXX_FLAGS CACHE CMAKE_CXX_FLAGS PROPERTY VALUE)
+  string(REPLACE " " ";" LIBUNWIND_CXX_FLAGS "${LIBUNWIND_CXX_FLAGS}")
+  list(APPEND CLANG_COMMAND ${LIBUNWIND_CXX_FLAGS})
   execute_process(
       COMMAND ${CLANG_COMMAND}
       RESULT_VARIABLE HAD_ERROR
       OUTPUT_VARIABLE LIBRARY_FILE
   )
   string(STRIP "${LIBRARY_FILE}" LIBRARY_FILE)
   file(TO_CMAKE_PATH "${LIBRARY_FILE}" LIBRARY_FILE)
   string(REPLACE "builtins" "${name}" LIBRARY_FILE "${LIBRARY_FILE}")