C++: Fix invalid read in isQtReservedWord()

The change

    CPlusPlus: Fix isQtReservedWord
    commit 7d76dd0079

enabled the problematic code path.

Change-Id: Ic89e3976b07ad55976c474f9c4b6d6f6cf64d29e
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/libs/cplusplus/pp-engine.cpp

@@ -99,7 +99,7 @@ static bool isQtReservedWord(const char *name, int size)
             size -= 2;
             switch (size) {
             case 1:
-                return name[2] == 'D' || name[2] == 'Q';
+                return name[0] == 'D' || name[0] == 'Q';
             case 4:
                 return same(name, "SLOT", size) || same(name, "EMIT", size);
             case 5: