windows: Use predefined RC_INVOKED macro instead of custom one

cmake/module/AddWindowsResources.cmake

@@ -7,9 +7,6 @@ include_guard(GLOBAL)
 function(add_windows_resources target rc_file)
   if(WIN32)
     target_sources(${target} PRIVATE ${rc_file})
-    set_property(SOURCE ${rc_file}
-      APPEND PROPERTY COMPILE_DEFINITIONS WINDRES_PREPROC
-    )
   endif()
 endfunction()
 

src/clientversion.h

@@ -17,13 +17,8 @@
 //! Copyright string used in Windows .rc files
 #define COPYRIGHT_STR "2009-" STRINGIZE(COPYRIGHT_YEAR) " " COPYRIGHT_HOLDERS_FINAL
 
-/**
- * bitcoind-res.rc includes this file, but it cannot cope with real c++ code.
- * WINDRES_PREPROC is defined to indicate that its pre-processor is running.
- * Anything other than a define should be guarded below.
- */
-
-#if !defined(WINDRES_PREPROC)
+// Windows .rc files include this header, but they cannot cope with real C++ code.
+#if !defined(RC_INVOKED)
 
 #include <string>
 #include <vector>
@@ -44,6 +39,6 @@ std::string CopyrightHolders(const std::string& strPrefix);
 /** Returns licensing information (for -version) */
 std::string LicenseInfo();
 
-#endif // WINDRES_PREPROC
+#endif // RC_INVOKED
 
 #endif // BITCOIN_CLIENTVERSION_H