Correctly set COMPILER_RT_HAS_BFLOAT16

Author: ndrewh

compiler-rt/lib/builtins/CMakeLists.txt

@@ -946,6 +946,7 @@ else ()
       check_c_source_compiles("__bf16 foo(__bf16 x) { return x; }
                                int main(void) { return 0; }"
                               COMPILER_RT_HAS_${arch}_BFLOAT16)
+      append_list_if(COMPILER_RT_HAS_${arch}_BFLOAT16 -DCOMPILER_RT_HAS_BFLOAT16 BUILTIN_CFLAGS_${arch})
       # Build BF16 files only when "__bf16" is available.
       if(COMPILER_RT_HAS_${arch}_BFLOAT16)
         list(APPEND ${arch}_SOURCES ${BF16_SOURCES})