#266 Fail to build from source on GNU/Hurd

[Alexander GQ Gerasiov]

You are widely using PATH_MAX and MAXPATHLEN defines.
According to POSIX those defines are not mandatory and system could not to provide them if there are no such limits.
Thus minidlna build failed on GNU/Hurd system.

More details are here:
https://www.gnu.org/software/hurd/hurd/porting/guidelines.html

[Florian Will]

The recommended fix by dynamically allocating/freeing growing chunks of memory until a chunk is big enough might be the ideal solution, but it's a lot of work for a niche OS and probably error-prone, while it clutters the code unnecessarily.

This fix, that some may consider "sloppy", is much easier to apply and won't break anything on systems that define PATH_MAX etc. It should be enough until we start using pictures taken with mobile phones for directory names:
https://github.com/archhurd/packages/blob/master/extra/rxvt-unicode-256color/hurd-path-max.diff

+#ifndef PATH_MAX
+#define PATH_MAX 16384
+#endif