[PATCH] [ASan tests] Make simple pthread tests compile and pass on Windows

[Kostya Serebryany]

LGTM with a small nit

================
Comment at: lib/sanitizer_common/tests/sanitizer_pthread_wrappers.h:66
@@ +65,3 @@
+}
+#endif
+
----------------
#endif  // _WIN32

http://reviews.llvm.org/D3725