pager: inline _pagersubprocess() into _runpager()

We don't need _pagersubprocess() because the fork version was removed
at 59d794154e8d.

hgext/pager.py

@@ -65,7 +65,7 b' from mercurial.i18n import _'
 # leave the attribute unspecified.
 testedwith = 'internal'
 
-def _pagersubprocess(ui, p):
+def _runpager(ui, p):
     pager = subprocess.Popen(p, shell=True, bufsize=-1,
                              close_fds=util.closefds, stdin=subprocess.PIPE,
                              stdout=sys.stdout, stderr=sys.stderr)
@@ -85,9 +85,6 b' def _pagersubprocess(ui, p):'
         os.dup2(stderr, sys.stderr.fileno())
         pager.wait()
 
-def _runpager(ui, p):
-    _pagersubprocess(ui, p)
-
 def uisetup(ui):
     if '--debugger' in sys.argv or not ui.formatted():
         return