Speed up QTimeZone::isTimeZoneIdAvailable by a factor 43

Creating and sorting a list of bytearrays just to check if one entry is
present, is really overkill. By adding a new virtual method
isTimeZoneIdAvailable() in the backend classes, we can do this much more
efficiently.

Implemented for Utc and Tz backends, the others fall back to the
slow way.

The new benchmark shows, in release mode:
Before: 43 msecs per iteration (total: 86, iterations: 2)
After: 1.1 msecs per iteration (total: 73, iterations: 64)

Change-Id: Ic0d79a41d74e2ce6aa088fa7986c41d33902c36b
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

0 files changed, 0 insertions, 0 deletions