QHash: remove optimization for QHash<int, T>

QHash: remove optimization for QHash<int, T>

QHash employs an optimization for int/uints, squashing the hash
value and the key value inside an union. This obviously works
iff qHash(int k) = k. If the hash value gets salted, the hash
table is corrupted.

This patch removes that optimization by means of a #if 0,
so if further research finds out that we want those 4 bytes back
it's pretty simple to revert.

Change-Id: If273f0bf2ff007f4f2f7c46d2aab364a3b455cf1
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>