[Bug c++/106102] gcc/cp/mapper-resolver.cc fails to build against musl: musl-1.2.3-dev/include/sched.h:84:7: error: attempt to use poisoned "calloc"

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106102

--- Comment #6 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
Also found a closely related jit build failure, but there <pthread.h> is used
directly.

Proposed the change to move <pthread.h> before poisoning step as:
https://gcc.gnu.org/pipermail/gcc-patches/2022-June/597379.html