man7/*: srcfix: trim trailing space

man7/*: srcfix: trim trailing space

  Trim tailing space in "strings".

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

###

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

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

troff: <attributes.7>:510: warning: trailing space
troff: <attributes.7>:512: warning: trailing space
troff: <attributes.7>:513: warning: trailing space
troff: <attributes.7>:516: warning: trailing space
troff: <attributes.7>:649: warning: trailing space
troff: <attributes.7>:681: warning: trailing space
troff: <attributes.7>:720: warning: trailing space
####

troff: <environ.7>:181: warning: trailing space
troff: <environ.7>:182: warning: trailing space
####

troff: <ip.7>:820: warning: trailing space
####

troff: <signal.7>:316: warning: trailing space
Signed-off-by: Bjarni Ingi Gislason <bjarniig@rhi.hi.is>
####

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>