Don't call memset if malloc returns a null pointer

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16797 91177308-0d34-0410-b5e6-96231b3b80d8

runtime/GCCLibraries/libc/memory.c

@@ -28,5 +28,6 @@ void *calloc(size_t nelem, size_t elsize) __ATTRIBUTE_WEAK__;
 
 void *calloc(size_t nelem, size_t elsize) {
   void *Result = malloc(nelem*elsize);
-  return memset(Result, 0, nelem*elsize);
+  if (Result) memset(Result, 0, nelem*elsize);
+  return Result;
 }