runtime: use _URC_FAILURE on ARM32

ARM32 EABI unwinder does not define _URC_NORMAL_STOP. Instead,
it has _URC_FAILURE. Use _URC_FAILURE there.

Should fix ARM32 build.

Change-Id: I68973bf4a153da344e6ed3e1b39c0492abcf8472
Reviewed-on: https://go-review.googlesource.com/c/153417
Reviewed-by: Ian Lance Taylor <iant@golang.org>
1 file changed