Fix /proc pathname sizes on Solaris

Fix /proc pathname sizes on Solaris

I'm slowly working my way through the gdb patches from the
solaris-userland repo

	https://github.com/oracle/solaris-userland/tree/master/components/gdb/patches

This one (001-fix-proc-name-size.patch) should be obvious given the
patches' comment:

# In Solaris, PID_MAX is 999999 (6 digit pid).
# In Solaris, lwpid_t is an unsigned int, so theoretically the lwp id
# could be 10 digits.

Tested on i386-pc-solaris2.11.

2018-09-19  Stefan Teleman <stefan.teleman@oracle.com>
	    April Chin <april.chin@oracle.com>
	    Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	* procfs.c (MAX_PROC_NAME_SIZE): Allow for 6-digit PID_MAX and
	uint_t lwpid_t.
	(create_procinfo): Print pids in /proc without leading zeros.