share: move config item declarations into core stable

share: move config item declarations into core

These config items control share behavior that is implemented in core.
Since the functionality is implemented in core, extensions may
leverage it.

Mozilla has one such extension. And, it needs to access share.pool.
Before this patch, a devel warning regarding accessing an unregistered
config option would be issued unless the share extension were loaded.
Moving the registration of the config options to core fixes this.

--- a/hgext/share.py	Sat Nov 04 23:39:54 2017 -0400
+++ b/hgext/share.py	Mon Nov 06 10:33:40 2017 -0800
@@ -63,16 +63,6 @@
 # leave the attribute unspecified.
 testedwith = 'ships-with-hg-core'
 
-configtable = {}
-configitem = registrar.configitem(configtable)
-
-configitem('share', 'pool',
-    default=None,
-)
-configitem('share', 'poolnaming',
-    default='identity',
-)
-
 @command('share',
     [('U', 'noupdate', None, _('do not create a working directory')),
      ('B', 'bookmarks', None, _('also share bookmarks')),

--- a/mercurial/configitems.py	Sat Nov 04 23:39:54 2017 -0400
+++ b/mercurial/configitems.py	Mon Nov 06 10:33:40 2017 -0800
@@ -790,6 +790,12 @@
 coreconfigitem('server', 'zliblevel',
     default=-1,
 )
+coreconfigitem('share', 'pool',
+    default=None,
+)
+coreconfigitem('share', 'poolnaming',
+    default='identity',
+)
 coreconfigitem('smtp', 'host',
     default=None,
 )