QList: Avoid implicit conversion warning

This fixes compiling an application using QList and -Wshorten-64-to-32
on a 64-bit system without getting this warning:

 ... 5.8/clang_64/lib/QtCore.framework/Headers/qlist.h:897:26:
 warning: implicit conversion loses integer precision: 'long' to 'int'
 [-Wshorten-64-to-32]
           int removedCount = e - n;
               ~~~~~~~~~~~~   ~~^~~

Change-Id: I688ed086805c431821c2ee6078fa5aeb631e7a07
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

src/corelib/tools/qlist.h

@@ -894,7 +894,7 @@ Q_OUTOFLINE_TEMPLATE int QList<T>::removeAll(const T &_t)
             *n++ = *i;
     }
 
-    int removedCount = e - n;
+    int removedCount = int(e - n);
     d->end -= removedCount;
     return removedCount;
 }