Improve compiler compatibility (#743)

* fix returns

* use standard C headers

* struct/class mismatch

* explicit this in template

* switch variable scope

* C standard compliance

* & l-value

src/JSystem/JMessage/processor.cpp

@@ -54,7 +54,7 @@ void TProcessor::pushCurrent(const char* v) {
 }
 
 /* 8029EEA4-8029EEC8       .text popCurrent__Q28JMessage10TProcessorFv */
-const char* TProcessor::popCurrent() {
+void TProcessor::popCurrent() {
     setCurrent_(mStack.top());
     mStack.pop();
 }