[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 #10 from Christopher Albert <albert at tugraz dot at> ---
Test results for the attached patch:

Linux x86_64 (local dev build): check-gfortran PASS
  0 FAIL, 0 XPASS, 3285 expected passes, 6 expected failures.
  Shmem CAF remains enabled (ac_cv_func_pthread_mutexattr_setpshared=yes).

cfarm428 (NetBSD 10.1, aarch64): build PASS, check-gfortran 421 failures
  Shmem CAF correctly disabled (ENABLE_CAF_SHMEM_TRUE='#').
  All 421 failures are pre-existing NetBSD/aarch64 platform issues:
  - coarray -lcaf_single tests: outline atomics linker errors (PR95129)
  - LTO link failures
  - proc_ptr, IEEE, and execution test failures
  None involve shmem CAF code.

OpenBSD (cfarm220, cfarm429): build test still in progress.
pthread_mutexattr_setpshared confirmed absent on both OpenBSD amd64
and aarch64, so the patch will also fix the build there.