Rename QSysInfo::cpuArchitecture and fullCpuArchitecture

To buildCpuArchitecture and buildAbi, respectively.

Change-Id: If84852eb4ef48a6e1fb4351f7a1a4434b4dc3f72
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>