Fix missing const-qualifiers in engine code. Fix qboolean/int mixing in interface implementations(int is preferred). Replace long by int in COM_RandomLong.

engine/common/zone.c

@@ -166,7 +166,7 @@ static const char *Mem_CheckFilename( const char *filename )
 
 	if( !out ) return dummy;
 	for( i = 0; i < 128; i++, out++ )
-		if( out == '\0' ) break; // valid name
+		if( *out == '\0' ) break; // valid name
 	if( i == 128 ) return dummy;
 	return filename;
 }
@@ -483,4 +483,4 @@ Memory_Init
 void Memory_Init( void )
 {
 	poolchain = NULL; // init mem chain
-}
+}