[pcp] pcp update: libpcp probe-discovery stacks

[Frank Ch. Eigler]

Hi -

This commit on pcpfans.git branch fche/libpcp-probestack
appears to correct RHBZ1319288.

commit 77755462f768415fb8833b6c77473df73faacea0
Author: Frank Ch. Eigler <fche at redhat.com>
Date:   Wed Mar 30 18:36:56 2016 -0400

    libpcp discovery probe: increase thread stack sizes
    
    In case pmDiscoverServices probe mode detects errors, pmNotifyErr() is
    called.  Its child pmprintf eats too many syscalls, and its grandchild
    pmGetConfig eats too much stack.  We cure the second gluttony by
    enlarging the thread stacks with a couple of MAXPATHLEN's, avoiding
    stack-overflow crashes.  qa/766 extended with "ulimit -n" based fault
    injection.