revset-rangeset: call 'getset' on a 'fullreposet'

Calling 'baseset(repo.changelog)' builds a list for all revisions in
the repo. And we already have the lazy and efficient 'fullreposet'
class for this purpose.

This gives us the usual benefit ofs the fullreposet:

revset) 10:100
before) wall 0.002774 comb 0.000000 user 0.000000 sys 0.000000 (best of 797)
after)  wall 0.001977 comb 0.000000 user 0.000000 sys 0.000000 (best of 1244)

revset) parents(10):parents(100)
before) wall 0.005054 comb 0.000000 user 0.000000 sys 0.000000 (best of 481)
after)  wall 0.002060 comb 0.000000 user 0.000000 sys 0.000000 (best of 1056)

mercurial/revset.py

@@ -265,9 +265,8 b' def symbolset(repo, subset, x):'
     return stringset(repo, subset, x)
 
 def rangeset(repo, subset, x, y):
-    cl = baseset(repo.changelog)
-    m = getset(repo, cl, x)
-    n = getset(repo, cl, y)
+    m = getset(repo, fullreposet(repo), x)
+    n = getset(repo, fullreposet(repo), y)
 
     if not m or not n:
         return baseset()