build/clang_darwin: Improve archs check to verify we can not just recognize

arch, but actually compile a file with that arch.

llvm-svn: 132928

compiler-rt/make/platform/clang_darwin.mk

@@ -12,7 +12,7 @@ CheckArches = \
   $(shell \
     result=""; \
     for arch in $(1); do \
-      if $(CC) -arch $$arch -dumpversion > /dev/null; then \
+      if $(CC) -arch $$arch -c -x c /dev/null -o /dev/null; then \
         result="$$result$$arch "; \
       fi; \
     done; \