Add .x as XDR/RPCGEN (#3472)

* Add .x as XDR/RPCGEN

XDR/RPC language as documented in RFC5531, RFC4506.
Samples are from glibc and RFCs.

* Add Logos samples

https://github.com/JonasGessner/NoCarrier/blob/master/NoCarrier.x - MIT
cf31f4e466/llvm-gcc-R3/gcc/testsuite/objc/execute/string1.x - GPL2
f6415578fa/perapp-plugin/Tweak.x - GPL3
d1b3e83888/NCHax.x - Apache

* Add disambiguate heuristics for .x

* Add RPC to vendor/README.md

samples/Logos/NoCarrier.x

@@ -0,0 +1,42 @@
+//
+//  NoCarrier.x
+//  NoCarrier
+//
+//  Created by Jonas Gessner on 27.01.2014.
+//  Copyright (c) 2014 Jonas Gessner. All rights reserved.
+//
+
+#import <CoreGraphics/CoreGraphics.h>
+
+#include <substrate.h>
+
+%group main
+
+%hook UIStatusBarServiceItemView
+
+- (id)_serviceContentsImage {
+    return nil;
+}
+
+- (CGFloat)extraLeftPadding {
+    return 0.0f;
+}
+
+- (CGFloat)extraRightPadding {
+    return 0.0f;
+}
+
+- (CGFloat)standardPadding {
+    return 2.0f;
+}
+
+%end
+
+%end
+
+
+%ctor {
+	@autoreleasepool {
+		%init(main);
+	}
+}