[Bug fortran/124512] [16 Regression] libgfortran shmem caf: NetBSD has no pthread_condattr_setpshared

[albert at tugraz dot at]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124512

--- Comment #9 from Christopher Albert <albert at tugraz dot at> ---
Created attachment 63969
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=63969&action=edit
Proposed patch: disable shmem CAF when pthread_mutexattr_setpshared is absent

Proposed patch attached.

This adds an AC_CHECK_FUNC for pthread_mutexattr_setpshared after AX_PTHREAD
in libgfortran/configure.ac.  When the function is absent (NetBSD, OpenBSD),
ENABLE_CAF_SHMEM is set to false and the shmem CAF library is not built.

Also adds aarch64*-*-netbsd* to the host detection pattern in gcc/config.host
for host_detect_local_cpu (matching the existing arm*-*-netbsd* pattern).

Tested so far:
- cfarm428 (NetBSD 10.1, aarch64): full build succeeds, shmem CAF correctly
  disabled (ENABLE_CAF_SHMEM_TRUE='#'), no thread_support.o built.
- Linux x86_64 (local): build succeeds, shmem CAF remains enabled.
  check-gfortran running (0 failures so far).
- cfarm220 (OpenBSD 7.8, amd64): pthread_mutexattr_setpshared confirmed absent.
  Build test in progress.
- cfarm428 check-gfortran also in progress.

Platform survey of pthread_mutexattr_setpshared availability:
  NetBSD 10.1 aarch64 (cfarm428): absent
  OpenBSD 7.8 amd64   (cfarm220): absent
  OpenBSD 7.8 aarch64 (cfarm429): absent
  FreeBSD 16  aarch64 (cfarm427): present
  DragonFly 6.4 amd64 (cfarm152): present
  GNU/Hurd    amd64   (cfarm431): present

Will follow up with full test results.