Get libbase tests working on Windows.

Tests using files from /proc still fail on Windows (obviously), but
all tests are passing when run in Wine.

Change-Id: Ie4c3ba65b642202f8fcaec73332a53bee6115fba
diff --git a/base/file_test.cpp b/base/file_test.cpp
index a7f070d..cbb2751 100644
--- a/base/file_test.cpp
+++ b/base/file_test.cpp
@@ -55,6 +55,9 @@
   EXPECT_EQ("abc", s);
 }
 
+// WriteStringToFile2 is explicitly for setting Unix permissions, which make no
+// sense on Windows.
+#if !defined(_WIN32)
 TEST(file, WriteStringToFile2) {
   TemporaryFile tf;
   ASSERT_TRUE(tf.fd != -1);
@@ -71,6 +74,7 @@
     << strerror(errno);
   EXPECT_EQ("abc", s);
 }
+#endif
 
 TEST(file, WriteStringToFd) {
   TemporaryFile tf;