to work with iOS13, we need XCode11. to use XCode11, we need to fix a…

… bug in RN0.5x.x.

or we will run into "Unknown argument type '__attribute__' in method" when start our app.
see this post for the bug:facebook#25138
this pr for the fix: https://github.com/facebook/react-native/pull/25146/files

React/Base/RCTModuleMethod.mm

@@ -91,7 +91,8 @@ static BOOL RCTParseSelectorPart(const char **input, NSMutableString *selector)
 static BOOL RCTParseUnused(const char **input)
 {
   return RCTReadString(input, "__attribute__((unused))") ||
-         RCTReadString(input, "__unused");
+       RCTReadString(input, "__attribute__((__unused__))") ||
+       RCTReadString(input, "__unused");
 }
 
 static RCTNullability RCTParseNullability(const char **input)
@@ -143,20 +144,20 @@ static BOOL checkCallbackMultipleInvocations(BOOL *didInvoke) {
     // Parse type
     if (RCTReadChar(&input, '(')) {
       RCTSkipWhitespace(&input);
-      
+
       // 5 cases that both nullable and __unused exist
       // 1: foo:(nullable __unused id)foo 2: foo:(nullable id __unused)foo
       // 3: foo:(__unused id _Nullable)foo 4: foo:(id __unused _Nullable)foo
       // 5: foo:(id _Nullable __unused)foo
       RCTNullability nullability = RCTParseNullability(&input);
       RCTSkipWhitespace(&input);
-      
+
       BOOL unused = RCTParseUnused(&input);
       RCTSkipWhitespace(&input);
 
       NSString *type = RCTParseType(&input);
       RCTSkipWhitespace(&input);
-      
+
       if (nullability == RCTNullabilityUnspecified) {
         nullability = RCTParseNullabilityPostfix(&input);
         RCTSkipWhitespace(&input);