QList: Remove CapacityReserved on squeeze

Even if we don't reallocate or detach.

Change-Id: I44928c261f037b304de8ee6135b96f00dd217c51
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>

src/corelib/tools/qlist.h

@@ -528,6 +528,9 @@ inline void QList<T>::squeeze()
             detached->copyAppend(constBegin(), constEnd());
         }
         d.swap(detached);
+    } else {
+        // We're detached so this is fine
+        d->clearFlag(Data::CapacityReserved);
     }
 }