Import libusb 1.0.9-rc3 into third_party

third_party/libusb/libusb/os/threads_posix.c

Index: third_party/libusb/libusb/os/threads_posix.c
diff --git a/third_party/libusb/libusb/os/threads_posix.c b/third_party/libusb/libusb/os/threads_posix.c
new file mode 100644
index 0000000000000000000000000000000000000000..435b8736ba97f6f351300799b15f01f81f66b086
--- /dev/null
+++ b/third_party/libusb/libusb/os/threads_posix.c
@@ -0,0 +1,55 @@
+/*
+ * libusb synchronization using POSIX Threads
+ *
+ * Copyright (C) 2011 Vitali Lovich <vlovich@aliph.com>
+ * Copyright (C) 2011 Peter Stuge <peter@stuge.se>
+ *
+ * This library 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.
+ *
+ * This library 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifdef _XOPEN_SOURCE
+# if _XOPEN_SOURCE < 500
+#  undef _XOPEN_SOURCE
+#  define _XOPEN_SOURCE 500
+# endif
+#else
+#define _XOPEN_SOURCE 500
+#endif /* _XOPEN_SOURCE */
+
+#include <pthread.h>
+
+int usbi_mutex_init_recursive(pthread_mutex_t *mutex, pthread_mutexattr_t *attr)
+{
+	int err;
+	pthread_mutexattr_t stack_attr;
+	if (!attr) {
+		attr = &stack_attr;
+		err = pthread_mutexattr_init(&stack_attr);
+		if (err != 0)
+			return err;
+	}
+
+	err = pthread_mutexattr_settype(attr, PTHREAD_MUTEX_RECURSIVE);
+	if (err != 0)
+		goto finish;
+
+	err = pthread_mutex_init(mutex, attr);
+
+finish:
+	if (attr == &stack_attr)
+		pthread_mutexattr_destroy(&stack_attr);
+
+	return err;
+}