platform/clang_darwin: Improve the "can we build for this arch test" by checking

that the standard includes we use in compiler-rt also work.

llvm-svn: 144305

compiler-rt/make/platform/clang_darwin.mk

@@ -12,7 +12,8 @@ CheckArches = \
   $(shell \
     result=""; \
     for arch in $(1); do \
-      if $(CC) -arch $$arch -c -x c /dev/null \
+      if $(CC) -arch $$arch -c \
+	  $(ProjSrcRoot)/make/platform/clang_darwin_test_input.c \
 	  -o /dev/null > /dev/null 2> /dev/null; then \
         result="$$result$$arch "; \
       fi; \

compiler-rt/make/platform/clang_darwin_test_input.c

@@ -0,0 +1,5 @@
+/* Include the headers we use in int_lib.h, to verify that they work. */
+
+#include <limits.h>
+#include <stdint.h>
+#include <math.h>