btrfs-progs: update to version 4.5.1

musl pthread patch imported from alpinelinux.org

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

utils/btrfs-progs/patches/0001-use-pthread_join-instead-of-pthread_tryjoin_np.patch

@@ -0,0 +1,11 @@
+--- btrfs-progs-v4.2.3/chunk-recover.c
++++ btrfs-progs-v4.2.3/chunk-recover.c.new
+@@ -883,7 +883,7 @@
+ 		for (i = 0; i < devidx; i++) {
+ 			if (dev_scans[i].bytenr == -1)
+ 				continue;
+-			ret = pthread_tryjoin_np(t_scans[i],
++			ret = pthread_join(t_scans[i],
+ 						 (void **)&t_rets[i]);
+ 			if (ret == EBUSY) {
+ 				all_done = 0;