revset: changed sort method to use native sort implementation of smartsets

When sort is done by revision or reversed revision number it can just call
sort on the set and doesn't have to iterate it all over again.

mercurial/revset.py

@@ -1492,7 +1492,14 b' def sort(repo, subset, x):'
     l = []
     def invert(s):
         return "".join(chr(255 - ord(c)) for c in s)
-    for r in getset(repo, subset, s):
+    revs = getset(repo, subset, s)
+    if keys == ["rev"]:
+        revs.sort()
+        return revs
+    elif keys == ["-rev"]:
+        revs.sort(reverse=True)
+        return revs
+    for r in revs:
         c = repo[r]
         e = []
         for k in keys: