[RemoteMirrors] Remove unused PipeMemoryReader_getSizeSize function.

Author: mikeash

tools/swift-reflection-test/swift-reflection-test.c

@@ -72,11 +72,6 @@ uint8_t PipeMemoryReader_getPointerSize(void *Context) {
   return sizeof(uintptr_t);
 }
 
-static
-uint8_t PipeMemoryReader_getSizeSize(void *Context) {
-  return sizeof(size_t);
-}
-
 static
 void PipeMemoryReader_collectBytesFromPipe(const PipeMemoryReader *Reader,
                                            void *Dest, size_t Size) {