[Dovecot] Patch for pigeonhole 0.4.0 avoiding PATH_MAX

Hi,

I recently downloaded and built dovecot-2.2.2 and dovecot-2.2-pigeonhole-0.4.0 on GNU/Linux and GNU/Hurd. The changes needed will be sent to the Debian maintainer shortly. Latest Debian release is 2.1.7-7 and dovecot-2.1-pigeonhole-0.3.1. When building dovecot-2.2.2 there were no PATH_MAX problems on GNU/Hurd, thank you for that. However, pigeonhole 0.4.0 had one remaining PATH_MAX construct. The attached patch solves this problem. It it good enough to be accepted upstream? (According to the description of t_malloc, free is not needed, right?)

Thanks, Svante Signell