- fixed a few compilation warnings

src/d_main.cpp:280:18: warning: using the result of an assignment as a condition without parentheses [-Wparentheses]
src/rendering/r_videoscale.cpp:147:22: warning: comparison of integers of different signs: 'int' and 'unsigned long' [-Wsign-compare]
src/sound/s_reverbedit.cpp:250:18: warning: comparison of integers of different signs: 'size_t' (aka 'unsigned long') and 'int' [-Wsign-compare]

src/rendering/r_videoscale.cpp

@@ -144,7 +144,7 @@ namespace
 	};
 	bool isOutOfBounds(int x)
 	{
-		return (x < 0 || x >= NUMSCALEMODES || vScaleTable[x].isValid == false);
+		return (x < 0 || x >= int(NUMSCALEMODES) || vScaleTable[x].isValid == false);
 	}
 }