re: toolchain/49434: gcc can not compile libasan with -O2 on vax

[matthew green <mrg%eterna.com.au@localhost>]

>  This is most likely fixed by Maciej W. Rozycki in:
>  https://github.com/gcc-mirror/gcc/commit/fbe575958c2ec322ac1703a14737a95e6036c4e0

while that might be a good fix to pull over if we don't have it
already in GCC 9 or 10, libasan has built on vax for a while.

it doesn't *works* but it builds, which was the original
problem here.

simply refuses to run:

cc1: warning: '-fsanitize=address' not supported for this target


.mrg.