win: Disable Clock tests that require SleepNanoseconds

As it was left unimplemented on Windows per previous discussion.

R=mark@chromium.org
BUG=crashpad:1

Review URL: https://codereview.chromium.org/838833004

util/misc/clock_test.cc

@@ -41,14 +41,18 @@ TEST(Clock, ClockMonotonicNanoseconds) {
     EXPECT_GE(now, last);
   }
 
+#if !defined(OS_WIN)  // No SleepNanoseconds implemented on Windows.
   // SleepNanoseconds() should sleep for at least the value of the clock’s
   // resolution, so the clock’s value should definitely increase after a sleep.
   // EXPECT_GT can be used instead of EXPECT_GE after the sleep.
   SleepNanoseconds(1);
   now = ClockMonotonicNanoseconds();
   EXPECT_GT(now, start);
+#endif  // OS_WIN
 }
 
+#if !defined(OS_WIN)  // No SleepNanoseconds implemented on Windows.
+
 void TestSleepNanoseconds(uint64_t nanoseconds) {
   uint64_t start = ClockMonotonicNanoseconds();
 
@@ -87,6 +91,8 @@ TEST(Clock, SleepNanoseconds) {
   }
 }
 
+#endif  // OS_WIN
+
 }  // namespace
 }  // namespace test
 }  // namespace crashpad