misc: eliminate a couple of miscellaneous gcc warnings

misc: eliminate a couple of miscellaneous gcc warnings

This commit just addresses those warnings shown below.

Reference(s):
proc/sysinfo.c: In function `getrunners':
proc/sysinfo.c:491:26: warning: `%s' directive writing up to 255 bytes into a region of size 26 [-Wformat-overflow=]
  491 |     sprintf(tbuf, "/proc/%s/stat", ent->d_name);
      |                          ^~

pgrep.c: In function `select_procs':
pgrep.c:591:11: warning: suggest explicit braces to avoid ambiguous `else' [-Wdangling-else]
  591 |   else if (opt_older)
      |           ^

Signed-off-by: Jim Warner <james.warner@comcast.net>