Don't set "-O0 -g" C flags when -debug is given

-debug now only determines whether or not a debug RTS is linked in.
To get main() with debugging symbols you need to explicitly say
    -optc-O0 -optc-g

compiler/main/DynFlags.hs

@@ -1062,7 +1062,7 @@ wayOptc platform WayThreaded = case platformOS platform of
                                OSOpenBSD -> ["-pthread"]
                                OSNetBSD  -> ["-pthread"]
                                _         -> []
-wayOptc _ WayDebug      = ["-O0", "-g"]
+wayOptc _ WayDebug      = []
 wayOptc _ WayDyn        = []
 wayOptc _ WayProf       = ["-DPROFILING"]
 wayOptc _ WayEventLog   = ["-DTRACING"]