pthread: Add pthread_yield()

Calls the more standard sched_yield().

CHANGELOG.rst

@@ -8,6 +8,15 @@
   © 2016-2019 Adélie Linux and contributors.  NCSA open source licence.
 
 
+0.9.1 (2020-08-??)
+==================
+
+pthread
+-------
+
+* Add pthread_yield from Hal G.
+
+
 0.9.0 (2020-07-06)
 ==================
 

libgcompat/pthread.c

@@ -2,6 +2,7 @@
 #include <errno.h>   /* errno */
 #include <fcntl.h>   /* O_CLOEXEC, O_RDONLY */
 #include <pthread.h> /* pthread_atfork */
+#include <sched.h>   /* sched_yield */
 #include <unistd.h>  /* open, read */
 
 #include "alias.h" /* weak_alias */
@@ -52,3 +53,11 @@ int pthread_getname_np(pthread_t thread, char *name, size_t len)
 
 	return 0;
 }
+
+/**
+ * Yield this thread.
+ */
+int pthread_yield(void)
+{
+	return sched_yield();
+}