proc.5: srcfix: trim trailing space

proc.5: srcfix: trim trailing space

Output is from: test-groff -b -mandoc -T utf8 -rF0 -t -w w -z

  [ "test-groff" is a developmental version of "groff" ]

Input file is ./proc.5

troff: <proc.5>:4410: warning: trailing space
troff: <proc.5>:5206: warning: trailing space
troff: <proc.5>:5488: warning: trailing space

###

  There is no change in the output from "nroff" and "groff".

Signed-off-by: Bjarni Ingi Gislason <bjarniig@rhi.hi.is>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>