define PATH_MAX in case it is not available

[mr-c]

this is needed to compile on hurd_i386

[jkbonfield]

Thanks for the patch.

I'm thinking this is perhaps ideal for io_lib/os.h as that's where we tend to put all the other system tweaks. Did you try this?

[mr-c]

@jkbonfield I didn't try that, but that is fine by me.

[jkbonfield]

Thanks. Fixed as 2f4305c by moving to io_lib/os.h.in