Generate a runtime error on recursive I/O, thread-safe

Generate a runtime error on recursive I/O, thread-safe

This patch is a version of Jerry's patch with one additional feature.
When locking a unit, the thread ID of the locking thread also stored
in the gfc_unit structure. When the unit is found to be locked, it can
be either have been locked by the same thread (bad, recursive I/O) or
by another thread (harmless).

Regression-tested fully (make -j8 check in the gcc build directory) on
Linux, which links in pthreads by default.  Steve checked on FreeBSD,
which does not do so.

Jerry DeLisle  <jvdelisle@gcc.gnu.org>
Thomas Koenig <tkoenig@gcc.gnu.org>

PR libfortran/119136

gcc/fortran/ChangeLog:

	* libgfortran.h: Add enum for new LIBERROR_RECURSIVE_IO.

libgfortran/ChangeLog:

	* io/async.h (UNLOCK_UNIT): New macro.
	(TRYLOCK_UNIT): New macro.
	(LOCK_UNIT): New macro.
	* io/io.h: Delete prototype for unused stash_internal_unit.
	(check_for_recursive): Add prototype for this new function.
	* io/transfer.c (data_transfer_init): Add call to new
	check_for_recursive.
	* io/unit.c (delete_unit): Fix comment.
	(check_for_recursive): Add new function.
	(init_units): Use new macros.
	(close_unit_1): Likewise.
	(unlock_unit): Likewise.
	* io/unix.c (flush_all_units_1): Likewise.
	(flush_all_units): Likewise.
	* runtime/error.c (translate_error): : Add translation for
	"Recursive I/O not allowed runtime error message.

gcc/testsuite/ChangeLog:

	* gfortran.dg/pr119136.f90: New test.