target-ppc: Introduce tcheck Add a degenerate implementation of the Transaction Check (tcheck) instruction. Since transaction always immediately fail, this implementation simply sets CR[BF] to 0b1000, i.e. TDOOMED = 1 and MSR[TS] == 0. Signed-off-by: Tom Musta <tommusta@gmail.com> Signed-off-by: Alexander Graf <agraf@suse.de>