runtime: use #ifdef instead of #if for USING_SPLIT_STACK

USING_SPLIT_STACK is configured as defined/undefined, not 0/1.
Most of the places test USING_SPLIT_STACK with #ifdef, with a
few exceptions. This CL fixes the exceptions.

Change-Id: I4dd2d214f5c05a812214079bb2496a1344857907
Reviewed-on: https://go-review.googlesource.com/120596
Reviewed-by: Ian Lance Taylor <iant@golang.org>
1 file changed