jack: Support OSX

Previously, with JACK installed, the configure script would enable the
JACK indev; this broke on OS X due to an incomplete pthreads
implementation. Add some simple macros to map libdispatch to pthreads
on OS X.
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

compat/dispatch_semaphore/semaphore.h

+/*
+ * This file is part of Libav.
+ *
+ * Libav is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * Libav is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef COMPAT_DISPATCH_SEMAPHORE_SEMAPHORE_H
+#define COMPAT_DISPATCH_SEMAPHORE_SEMAPHORE_H
+
+#include <dispatch/dispatch.h>
+#include <errno.h>
+
+#define sem_t dispatch_semaphore_t
+#define sem_post(psem)              dispatch_semaphore_signal(*psem)
+#define sem_wait(psem)              dispatch_semaphore_wait(*psem, DISPATCH_TIME_FOREVER)
+#define sem_timedwait(psem, val)    dispatch_semaphore_wait(*psem, dispatch_walltime(val, 0))
+#define sem_destroy(psem)           dispatch_release(*psem)
+
+static inline int compat_sem_init(dispatch_semaphore_t *psem,
+                                  int unused, int val)
+{
+    int ret = !!(*psem = dispatch_semaphore_create(val)) - 1;
+    if (ret < 0)
+        errno = ENOMEM;
+    return ret;
+}
+
+#define sem_init compat_sem_init
+
+#endif /* COMPAT_DISPATCH_SEMAPHORE_SEMAPHORE_H */

configure

@@ -1447,6 +1447,7 @@ BUILTIN_LIST="
     MemoryBarrier
     mm_empty
     rdtsc
+    sem_timedwait
     sync_val_compare_and_swap
 "
 HAVE_LIST_CMDLINE="
@@ -1467,6 +1468,7 @@ HEADERS_LIST="
     arpa_inet_h
     cdio_paranoia_h
     cdio_paranoia_paranoia_h
+    dispatch_dispatch_h
     dev_bktr_ioctl_bt848_h
     dev_bktr_ioctl_meteor_h
     dev_ic_bt8xx_h
@@ -2300,7 +2302,8 @@ bktr_indev_deps_any="dev_bktr_ioctl_bt848_h machine_ioctl_bt848_h dev_video_bktr
 dv1394_indev_deps="dv1394"
 dv1394_indev_select="dv_demuxer"
 fbdev_indev_deps="linux_fb_h"
-jack_indev_deps="jack_jack_h pthreads"
+jack_indev_deps="jack_jack_h"
+jack_indev_deps_any="sem_timedwait dispatch_dispatch_h"
 libcdio_indev_deps="libcdio"
 libdc1394_indev_deps="libdc1394"
 oss_indev_deps_any="soundcard_h sys_soundcard_h"
@@ -3747,6 +3750,8 @@ case $target_os in
         enabled x86_64 && objformat="macho64"
         enabled_any pic shared ||
             { check_cflags -mdynamic-no-pic && add_asflags -mdynamic-no-pic; }
+        check_header dispatch/dispatch.h &&
+            add_cppflags '-I\$(SRC_PATH)/compat/dispatch_semaphore'
         ;;
     msys*)
         die "Native MSYS builds are discouraged, please use the MINGW environment.";
@@ -4503,6 +4508,9 @@ if ! disabled pthreads && ! enabled w32threads; then
     fi
 fi
 
+enabled pthreads &&
+    check_builtin sem_timedwait semaphore.h "sem_t *s; sem_init(s,0,0); sem_timedwait(s,0); sem_destroy(s)"
+
 disabled  zlib || check_lib   zlib.h      zlibVersion -lz   || disable  zlib
 disabled bzlib || check_lib2 bzlib.h BZ2_bzlibVersion -lbz2 || disable bzlib