CBD485-prereq: Add couchstore_set_purge_seq

In order to move the compactor into ep-engine for CBD-485
ep-engine needs to have a way to set the purge sequence number
Adding a new couchstore api routine
couchstore_set_purge_seq to set a sequence number into the header.

Change-Id: Id29f41d999a51604332fa0994a9be1c3b45c6a87
Reviewed-on: http://review.couchbase.org/29233
Reviewed-by: Aaron Miller <apage43@ninjawhale.com>
Tested-by: Aaron Miller <apage43@ninjawhale.com>
MB-8778: Allow zero views

The couch_view_file_sorter allows to have zero views.
That is needed for the incremental update of spatial
views, where the file sorter is only used fro the
id-btree, but not for the views themselves. The views
are updated within the Erlang space.

Change-Id: I5d1650d1479fa877e7f72e1970cdb111aedd8d36
Reviewed-on: http://review.couchbase.org/28055
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Tested-by: Volker Mische <volker.mische@gmail.com>
CBD-979: Revert file_name_utils to C

There seems to be a bug in the mingw compiler causing the build
to fail on windows.

Change-Id: I9e34a34d4e698c8c333ceee1681915f5062fd259
Disable stuff to test code

Change-Id: I833fd24968bf545548521aba09e0ec5b8f750d34