getpid() returns pid_t; format strings expected unsigned int.  gcc builds
fail without this change.

XXX file upstream bug; patch may not be correct solution

--- grilo-0.2.12/libs/net/grl-net-wc.c	2014-11-18 10:47:05.000000000 -0800
+++ grilo-0.2.12/libs/net/grl-net-wc.c	2015-07-09 09:39:48.083811259 -0700
@@ -545,7 +545,7 @@
 
   /* Append record about the just written file to "grl-net-mock-data-%PID.ini"
    * in the capture directory. */
-  char *filename = g_strdup_printf ("grl-net-mock-data-%u.ini", getpid());
+  char *filename = g_strdup_printf ("grl-net-mock-data-%u.ini", (unsigned int) getpid());
   path = g_build_filename (capture_dir, filename, NULL);
   g_free (filename);