tests/test-gendoc-da.t

chg: let procutil maintain its own pagerpid

Previously, chg.c maintains the pagerpid. Let's move it to procutil.c.

Note: chg.c still have a pagerpid to decide whether to call attachio or not.
In the future, attachio may be moved from hgc_open to hgc_runcommand, and
hgc_runcommand handles both pager and attachio so we don't need to run
attachio twice. And chg.c will be free of pagerpid.

#require docutils gettext

  $ $TESTDIR/check-gendoc da
  checking for parse errors