C11 threads: Move implementation to sysdeps/pthread

so it gets shared by nptl and htl. Also add htl versions of thrd_current and
thrd_yield.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

sysdeps/pthread/tst-cnd-basic.c

@@ -0,0 +1,80 @@
+/* C11 threads condition variable tests.
+   Copyright (C) 2018-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C 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.
+
+   The GNU C 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 the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <threads.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include <support/check.h>
+
+/* Shared condition variable between child and parent.  */
+static cnd_t cond;
+
+/* Mutex needed to signal and wait threads.  */
+static mtx_t mutex;
+
+static int
+signal_parent (void)
+{
+  /* Acquire the lock so that cnd_signal does not run until
+     cnd_timedwait has been called.  */
+  if (mtx_lock (&mutex) != thrd_success)
+    FAIL_EXIT1 ("mtx_lock failed");
+  if (cnd_signal (&cond) != thrd_success)
+    FAIL_EXIT1 ("cnd_signal");
+  if (mtx_unlock (&mutex) != thrd_success)
+    FAIL_EXIT1 ("mtx_unlock");
+
+  thrd_exit (thrd_success);
+}
+
+static int
+do_test (void)
+{
+  thrd_t id;
+
+  if (cnd_init (&cond) != thrd_success)
+    FAIL_EXIT1 ("cnd_init failed");
+  if (mtx_init (&mutex, mtx_plain) != thrd_success)
+    FAIL_EXIT1 ("mtx_init failed");
+
+  if (mtx_lock (&mutex) != thrd_success)
+    FAIL_EXIT1 ("mtx_lock failed");
+
+  if (thrd_create (&id, (thrd_start_t) signal_parent, NULL)
+      != thrd_success)
+    FAIL_EXIT1 ("thrd_create failed");
+
+  if (cnd_wait (&cond, &mutex) != thrd_success)
+    FAIL_EXIT1 ("cnd_wait failed");
+
+  /* Joining is not mandatory here, but still done to assure child thread
+     ends correctly.  */
+  if (thrd_join (id, NULL) != thrd_success)
+    FAIL_EXIT1 ("thrd_join failed");
+
+  if (mtx_unlock (&mutex) != thrd_success)
+    FAIL_EXIT1 ("mtx_unlock");
+
+  mtx_destroy (&mutex);
+  cnd_destroy (&cond);
+
+  return 0;
+}
+
+#include <support/test-driver.c>