Kernel: fix register corruption on signal delivery
Kernel: fix register corruption on signal delivery

This fixes problems with test79 and other programs.

Change-Id: I14de097a3b01114ec5dbd687ab5be9290ad13fc7

veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi