runtime: fix lfstackUnpack on ia64

The top three region number bits must be masked out before
right-shifting the address bits into place, otherwise they will be
copied down into the lower always-zero address bits.

Change-Id: Iae8bdfa23c61259948b9cf8e3c9a6c13b09ea3e7
Reviewed-on: https://go-review.googlesource.com/84535
Reviewed-by: Ian Lance Taylor <iant@golang.org>
1 file changed