lib/asan: Attempt to ensure __WORDSIZE gets defined, it is not always set by
Darwin's stdint.h for example.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@145663 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/asan/asan_internal.h b/lib/asan/asan_internal.h
index 16d8e42..89b9e20 100644
--- a/lib/asan/asan_internal.h
+++ b/lib/asan/asan_internal.h
@@ -22,6 +22,16 @@
 #include <stdlib.h>  // for size_t
 #include <unistd.h>  // for _exit
 
+// If __WORDSIZE was undefined by the platform, define it in terms of the
+// compiler built-in __LP64__.
+#ifndef __WORDSIZE
+#if __LP64__
+#define __WORDSIZE 64
+#else
+#define __WORDSIZE 32
+#endif
+#endif
+
 #ifdef ANDROID
 #include <sys/atomics.h>
 #endif