fix analyze warning in fcm (#2650)

Author: charlotteliang

Example/Messaging/Tests/FIRMessagingReceiverTest.m

@@ -47,6 +47,8 @@ - (void)tearDown {
 }
 
 - (void)testUseMessagingDelegate {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
   XCTAssertFalse(_messaging.useMessagingDelegateForDirectChannel);
 
   _messaging.useMessagingDelegateForDirectChannel = YES;
@@ -67,7 +69,7 @@ - (void)testUseMessagingDelegateFlagOverridedByPlistWithTrueValue {
   OCMStub([bundleMock objectForInfoDictionaryKey:kFIRMessagingPlistUseMessagingDelegate])
       .andReturn(@YES);
   XCTAssertTrue(_messaging.useMessagingDelegateForDirectChannel);
-
+#pragma clang diagnostic pop
   [bundleMock stopMocking];
 }
 @end