Add more entries to .gitignore

* .gitignore: Add /lib/poll.h, /lib/sys/select.h, /lib/sys/times.h,
  and /test-suite/standalone/test-scm-c-bind-keyword-arguments.
Improve error when 'include' form with relative path is not in a file.

Reported by Nala Ginrut <nalaginrut@gmail.com>.

* module/ice-9/psyntax.scm (include): Give a proper error message when
  given a relative file name, and when the form is not in a file.

* module/ice-9/psyntax-pp.scm: Regenerate.
Convert guile exceptions to R6RS conditions in R6RS exception handlers.

* module/rnrs/exceptions.scm (&guile): New condition type.

  (guile-condition-converters): New variable.

  (convert-guile-condition, default-guile-condition-converter,
  set-guile-condition-converter!, guile-common-conditions,
  guile-lexical-violation-converter, guile-syntax-violation-converter,
  guile-assertion-violation-converter, guile-system-error-converter,
  guile-undefined-violation-converter, guile-error-converter,
  guile-implementation-restriction-converter): New procedures.

  (with-exception-handler): Catch all exceptions, not just R6RS
  exceptions.  Convert native Guile exceptions to R6RS conditions,
  preserving the original Guile exception information in the &guile
  condition object.

  (raise): If the condition includes a &guile condition, use 'throw' to
  throw the original native guile exception instead of raising an R6RS
  exception.

* test-suite/tests/r6rs-exceptions.test ("guile condition conversions"):
  Add tests.
Add procedures to convert alists into hash tables.

* module/ice-9/hash-table.scm: New module.

* test-suite/tests/hash.test ("alist conversion"): Add tests.

* doc/ref/api-compound.texi (Hash Table Reference): Add docs.
THANKS David Thompson

* THANKS: Add David Thompson to list of contributors.
Web: accept "UTC" as the zone offset in date headers.

Fixes <http://bugs.gnu.org/14128>.
Reported by Aleix Conchillo Flaqué <aconchillo@gmail.com>.

* module/web/http.scm (parse-zone-offset): Accept "UTC".
Convert test-suite/tests/exceptions.test to use hygienic macros.

* test-suite/tests/exceptions.test (push): New syntax parameter.
  (throw-test): Convert to a syntax-rules macro, using syntax parameters
  to support the otherwise-unhygienic use of "push".
Add mutex locking functions that also block asyncs.

* libguile/async.h (scm_i_pthread_mutex_lock_block_asyncs,
  scm_i_pthread_mutex_unlock_unblock_asyncs): New macros.

* libguile/threads.c (do_unlock_with_asyncs): New static helper.
  (scm_i_dynwind_pthread_mutex_lock_block_asyncs): New function.

* libguile/threads.h (scm_i_dynwind_pthread_mutex_lock_block_asyncs):
  Add prototype.
Block system asyncs while 'overrides_lock' is held.

* libguile/procprop.c (scm_set_procedure_property_x): Block system
  asyncs while overrides_lock is held.  Use dynwind block in case
  an exception is thrown.
Make guardians thread-safe.

* libguile/guardians.c (t_guardian): Add mutex.
  (finalize_guarded, scm_i_guard, scm_i_get_one_zombie): Lock mutex and
  block system asyncs during critical sections.
  (scm_make_guardian): Initialize mutex.
Make port properties accessible from Scheme.

* libguile/ports.c (scm_i_port_alist, scm_i_set_port_alist_x): Removed.
  (scm_i_port_property, scm_i_set_port_property_x): New procedures,
  available from Scheme as '%port-property' and '%set-port-property!'.

* libguile/ports.h (scm_i_port_alist, scm_i_set_port_alist_x): Removed.
  (scm_i_port_property, scm_i_set_port_property_x): New prototypes.

* libguile/read.c (set_port_read_option, init_read_options): Adapt to
  use scm_i_port_property and scm_i_set_port_property_x.
Stylistic improvements for (ice-9 popen).

* module/ice-9/popen.scm (close-process, close-process-quietly): Accept
  'port' and 'pid' as separate arguments.  Improve style.
  (close-pipe, read-pipes): Improve style.
Make (ice-9 popen) thread-safe.

Fixes <http://bugs.gnu.org/15683>.
Reported by David Pirotte <david@altosw.be>.

* module/ice-9/popen.scm: Import (ice-9 threads) and (srfi srfi-9).
  (<pipe-info>): New record type.
  (port/pid-table): Mark as deprecated in comment.
  (port/pid-table-mutex): New variable.
  (open-pipe*): Store the pid in the pipe-info record, and store the
  pipe-info as a port property.  Guard the pipe-info instead of the
  port.  Lock 'port/pid-table-mutex' while mutating 'port/pid-table'.
  (fetch-pid): Removed.
  (fetch-pipe-info): New procedure.
  (close-process-quietly): Removed.
  (close-pipe): Use 'fetch-pipe-info' instead of 'fetch-pid'.  Clear
  the pid from the pipe-info.  Improve error messages.
  (reap-pipes): Adapt to the fact that the pipe-info is now guarded
  instead of the port.  Incorporate the 'waitpid' code that was
  previously in 'close-process-quietly', but let the port finalizer
  close the port.  Clear the pid from the pipe-info.