[CMake][Clang] Skip host link version detection for lld on Darwin

[phosek]

Summary

When lld is being used as host linker, skip version detection since
lld version cannot be used interchangeably with ld64 version and lld
is already handled specially in Clang driver.

[int3]

Thanks!

clang/CMakeLists.txt

if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
   check_cxx_compiler_flag("-Werror -Wnested-anon-types" CXX_SUPPORTS_NO_NESTED_ANON_TYPES_FLAG)
   if( CXX_SUPPORTS_NO_NESTED_ANON_TYPES_FLAG )
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-nested-anon-types" )
   endif()
 endif ()
 
 # Determine HOST_LINK_VERSION on Darwin.
 set(HOST_LINK_VERSION)
-if (APPLE)
+if (APPLE AND NOT CMAKE_LINKER MATCHES ".*lld.*")
   set(LD_V_OUTPUT)
   execute_process(
     COMMAND sh -c "${CMAKE_LINKER} -v 2>&1 | head -1"
     RESULT_VARIABLE HAD_ERROR
     OUTPUT_VARIABLE LD_V_OUTPUT
   )
   if (HAD_ERROR)
     message(FATAL_ERROR "${CMAKE_LINKER} failed with status ${HAD_ERROR}")