[Bug bootstrap/89864] [9 regression] gcc fails to build/bootstrap with XCode 10.2

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89864

--- Comment #61 from Iain Sandoe <iains at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #60)
> PR 81797 was the relevant bug, which apparently is still present for darwin
> when using the buggy new APFS filesystem

so, from discussion on IRC, and notes above, this seems to be a known issue
(with AFPS only) and the current remedy is to continue the bootstrap.

Let's consider that we have a viable work-around and then please can we wait
for a response from Apple and the clang devs before making a final fix?

(i.e. this is enough of a work-around to prevent folks from being blocked right
now)