1) Now KisSpontaneousJob has an 'exclusive' property, which guarantees
   that now other update jobs are not running in parallel

2) KisModifyTransformMaskCommand mush not call m_mask->recaclulateStaticImage()
   directly, it doesn't guarantee exclusive access to a paint device, which
   can cause a crash (because the transform worker calls KisPaintDevice::purge(),
   which demands exclusive access).

BUG:395224