[Bug libstdc++/64203] shared_mutex compile errors on bare-metal targets

[sandra at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64203

--- Comment #2 from Sandra Loosemore <sandra at codesourcery dot com> ---
(In reply to Jonathan Wakely from comment #1)
> Created attachment 34208 [details]
> fix config macros for shared_lock
> 
> Does this fix it?

No, with this patch I'm still getting the same undefined symbol errors about
defer_lock_t, try_to_lock_t, etc.

FAOD it looks like on this target _GLIBCXX_USE_C99_STDINT_TR1 is defined but
_GLIBCXX_HAS_GTHREADS is not.