Fix wrong #define checks for DEBUG macro

src/openrct2/OpenRCT2.cpp

@@ -397,7 +397,7 @@ namespace OpenRCT2
         {
             String::AppendFormat(buffer, bufferSize, " provided by %s", gBuildServer);
         }
-    #if DEBUG
+    #ifdef DEBUG
         String::AppendFormat(buffer, bufferSize, " (DEBUG)", gBuildServer);
     #endif
         _versionInfo = buffer;

src/openrct2/core/String.cpp

@@ -357,7 +357,7 @@ namespace String
             firstNonWhitespace != str)
         {
             size_t newStringSize = ch - firstNonWhitespace;
-#if DEBUG
+#ifdef DEBUG
             size_t currentStringSize = String::SizeOf(str);
             Guard::Assert(newStringSize < currentStringSize, GUARD_LINE);
 #endif

src/openrct2/drawing/Image.cpp

@@ -252,7 +252,7 @@ extern "C"
     {
         if (_allocatedImageCount != 0)
         {
-#if DEBUG
+#ifdef DEBUG
             Guard::Assert(_allocatedImageCount == 0, "%u images were not freed", _allocatedImageCount);
 #else
             Console::Error::WriteLine("%u images were not freed", _allocatedImageCount);

src/openrct2/interface/window.c

@@ -976,7 +976,7 @@ void widget_invalidate(rct_window *w, sint32 widgetIndex)
 	rct_widget* widget;
 
 	assert(w != NULL);
-#if DEBUG
+#ifdef DEBUG
 	for (sint32 i = 0; i <= widgetIndex; i++) {
 		assert(w->widgets[i].type != WWT_LAST);
 	}