Make sure that -gsplit-dwarf isn't passed to the linker.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187456 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/cmake/modules/HandleLLVMOptions.cmake b/cmake/modules/HandleLLVMOptions.cmake
index 88a4730..58ffb8d 100644
--- a/cmake/modules/HandleLLVMOptions.cmake
+++ b/cmake/modules/HandleLLVMOptions.cmake
@@ -263,7 +263,7 @@
 
 # Turn on -gsplit-dwarf if requested
 if(LLVM_USE_SPLIT_DWARF)
-  add_flag_if_supported("-gsplit-dwarf")
+  add_llvm_definitions("-gsplit-dwarf")
 endif()
 
 add_llvm_definitions( -D__STDC_CONSTANT_MACROS )