lvm2: update portability musl patch to unbreak cross arm/musl.

srcpkgs/lvm2/patches/portability.patch

@@ -47,3 +47,15 @@ Portability fixes:
  #include <errno.h>
  #include <pthread.h>
 
+--- libdm/libdm-timestamp.c.orig	2015-08-10 01:49:59.000000000 +0200
++++ libdm/libdm-timestamp.c	2015-08-11 08:20:26.324155251 +0200
+@@ -34,7 +34,9 @@
+ #ifdef HAVE_REALTIME
+ 
+ #include <time.h>
++#ifdef __GLIBC__
+ #include <bits/time.h>
++#endif
+ 
+ struct dm_timestamp {
+ 	struct timespec t;