Introduce QT_SUPPORTS_INT128 and QT_NO_INT128 marcos to handle 128-bit
types. These macros allow to undef Qt's own 128-bit types and the
related code, but keep the compiler definitions unchanged.
This is required for Qt Bluetooth, where we need to use
QT_BLUETOOTH_REMOVED_SINCE to get rid of the APIs using
QtBluetooth-specific struct quint128 which clashes with the 128-bit
types. The idea is to use QT_NO_INT128 in Qt Bluetooth's
removed_api.cpp instead of directly undef'ing __SIZEOF_INT128__,
because the latter is UB.
This commit amends befda1acca.
Pick-to: 6.6
Change-Id: Ia2c110b5744c3aaa53eda39fb44984cf5a01fac2
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>