Build fails on debian's gnu/Hurd-i386 arch

Hello,

As you can see in https://buildd.debian.org/status/fetch.php?pkg=beanstalkd&arch=hurd-i386&ver=1.8-1&stamp=1365546488 beanstalkd fails to build in hurd-i386 with: ```walg.c:408:15: error: 'PATH_MAX' undeclared (first use in this function)``` 
because there is no upper limit in pathnames. 
http://www.gnu.org/software/hurd/hurd/porting/guidelines.html#PATH_MAX_tt_MAX_PATH_tt_MAXPATHL suggests using dynamic allocation of memory.

I have written a patch and intend to include it in the next release of beanstalkd package. Could you please consider incorporating it upstream so i can drop the debian-specific patch sometime in the future?