Fix inverted gettimeofday() return value handling

The gettimeofday function returns 0 for success, not for failure. As a
result of the inverted logic we were losing millisecond precision when
parsing incoming messages on non-HAVE_CLOCK_GETTIME systems (macOS).

src/Message.cpp

@@ -225,7 +225,7 @@ void CMessage::InitTime() {
     }
 #endif
 
-    if (!gettimeofday(&m_time, nullptr)) {
+    if (gettimeofday(&m_time, nullptr)) {
         m_time.tv_sec = time(nullptr);
         m_time.tv_usec = 0;
     }

test/UtilsTest.cpp

@@ -96,11 +96,14 @@ TEST(UtilsTest, ServerTime) {
     EXPECT_EQ("2011-10-19T16:40:51.620Z", str1);
 
     timeval now;
-    if (!gettimeofday(&now, nullptr)) {
+    if (gettimeofday(&now, nullptr)) {
         now.tv_sec = time(nullptr);
         now.tv_usec = 0;
     }
 
+    // Strip microseconds, server time is ms only
+    now.tv_usec = (now.tv_usec / 1000) * 1000;
+
     CString str2 = CUtils::FormatServerTime(now);
     timeval tv2 = CUtils::ParseServerTime(str2);
     EXPECT_EQ(now.tv_sec, tv2.tv_sec);