[patch, libfortran] Restore bootstrap on FreeBSD (hopefully)

[Steve Kargl]

On Fri, Jan 09, 2026 at 08:57:25PM +0100, Thomas König wrote:
> As analyzed by Steve, on freebsd __gthread_t is a pointer type.
> I thought it the cleanest solution to remove the #ifdef in gfc_unit,
> make the "self" member a intptr_t and cast the return value of
> __gthread_t to that type.
> 
> Sorry for breaking bootstrap... the ubiquity of Linux is really
> striking here. There are a couple of
> 
> Regression-tested on Linux.  FreeBSD should also work, but I'd
> like confirmation, if possible. Steve, could you be so kind?
> 
> OK for trunk?
> 

Fixes bootstrap and regression tests cleanly.  Ok to commit.

Nothing to be sorry about!  Things can break
at the top-of-tree.  Plus, I learned something,
from the linux pthread_self() man page:

  POSIX.1 allows an implementation wide freedom in choosing the type
  used to represent a thread ID; for example, representation using
  either an arithmetic type or a structure is permitted.  Therefore,
  variables of type pthread_t can't portably be compared using the C
  equality operator (==); use pthread_equal(3) instead.

  Thread identifiers should be considered opaque: any attempt to use
  a thread ID other than in pthreads calls is nonportable and can
  lead to unspecified results.

-- 
Steve