Make qtbase compile with QT_NO_TEXTCODEC

Change-Id: I1614dc08c0dd1950020e415f37c97160431b2336
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Remove use of 'register' from Qt.

It is deprecated and clang is starting to warn about it.

Patch mostly generated by clang itself, with some careful grep
and sed for the platform-specific parts.

Change-Id: I8058e6db0f1b41b33a9e8f17a712739159982450
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>