setup.py: Add 'mercurial' as include dir for the inotify compiler.
This patch adds access to util.h for the inotify C module by adding the
"mercurial" directory as an include dir, enabling access to the macros defined
in util.h.
#!/bin/sh
hg init
touch a
hg add a
hg ci -m "a" -d "1000000 0"
echo 123 > b
hg add b
hg diff --nodates
hg diff --nodates -r tip
echo foo > a
hg diff --nodates
hg diff -r ""
hg diff -r tip -r ""
true