workqueue: add missing pthreads header

Fix the following build failure with musl libc:

In file included from read_verify.c:25:0:
../include/workqueue.h:39:2: error: unknown type name 'pthread_t'
  pthread_t  *threads;
  ^~~~~~~~~
../include/workqueue.h:42:2: error: unknown type name 'pthread_mutex_t'
  pthread_mutex_t  lock;
  ^~~~~~~~~~~~~~~
../include/workqueue.h:43:2: error: unknown type name 'pthread_cond_t'
  pthread_cond_t  wakeup;
  ^~~~~~~~~~~~~~

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/workqueue.h b/include/workqueue.h
index b4b3541701..edb2f8ac59 100644
--- a/include/workqueue.h
+++ b/include/workqueue.h
@@ -22,6 +22,8 @@
 #ifndef	_WORKQUEUE_H_
 #define	_WORKQUEUE_H_
 
+#include <pthread.h>
+
 struct workqueue;
 
 typedef void workqueue_func_t(struct workqueue *wq, uint32_t index, void *arg);