[Bug bootstrap/87498] Inconsistent behaviour for passing -DNO_ASM and host=none

[miro.kropacek at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87498

--- Comment #3 from Miro Kropacek <miro.kropacek at gmail dot com> ---
Fix is easy - just pass --disable-assembly to extra_configure_flags.

I guess gcc will have to deal with the 'none' target in the future anyway
because it is deprecated in gmp.