Fix includes if built against musl

LOCK_* is defined in sys/file.h

http://git.musl-libc.org/cgit/musl/tree/include/sys/file.h

Closes: #730
Approved by: cgwalters

src/libostree/ostree-repo.c

@@ -42,6 +42,7 @@
 
 #include <locale.h>
 #include <glib/gstdio.h>
+#include <sys/file.h>
 
 /**
  * SECTION:ostree-repo

src/libostree/ostree-sysroot.c

@@ -21,6 +21,7 @@
 #include "config.h"
 
 #include "otutil.h"
+#include <sys/file.h>
 #include <sys/mount.h>
 #include <sys/wait.h>