Use _M_ARM64 instead of _ARM64_.

Examples/MyProg/Myprog.c

@@ -5,7 +5,7 @@
 	#define ARCHNOTE TEXT("")
 #elif defined(_AMD64_)
 	#define ARCHNOTE TEXT("\n\n(This EXE was compiled for the x64 architecture.)")
-#elif defined(_ARM64_)
+#elif defined(_M_ARM64)
 	#define ARCHNOTE TEXT("\n\n(This EXE was compiled for the ARM64 architecture.)")
 #elif defined(_IA64_)
 	#define ARCHNOTE TEXT("\n\n(This EXE was compiled for the Itanium architecture.)")