common BUGFIX define PATH_MAX if not available

PATH_MAX is optional in POSIX, and thus may not be provided (e.g. on
GNU/Hurd). Provide a fallback definition for it, so the existing code
keeps working for now; include <limits.h> to ensure that PATH_MAX is
available if provided on the current OS/libc.

Author: pinotree

src/ly_common.h

@@ -20,6 +20,7 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <string.h>
+#include <limits.h>
 
 #include "compat.h"
 #include "context.h"
@@ -61,6 +62,11 @@ struct lysc_node;
 #define GETMACRO6(_1, _2, _3, _4, _5, _6, NAME, ...) NAME
 #define GETMACRO7(_1, _2, _3, _4, _5, _6, _7, NAME, ...) NAME
 
+/** optional in POSIX */
+#ifndef PATH_MAX
+# define PATH_MAX 4096
+#endif
+
 /******************************************************************************
  * Logger
  *****************************************************************************/