util: #define PATH_MAX when undefined (eg. Hurd)

Cc: Timo Aaltonen <tjaalton@debian.org>
Cc: James Clarke <jrtc27@debian.org>
Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>

src/util/xmlconfig.c

@@ -42,6 +42,10 @@
 #include "xmlconfig.h"
 #include "u_process.h"
 
+/* For systems like Hurd */
+#ifndef PATH_MAX
+#define PATH_MAX 4096
+#endif
 
 /** \brief Find an option in an option cache with the name as key */
 static uint32_t