Rename: rw-inl.c => rw-inl.h

We'd like to use globbing (e.g. *.c) for compilation to make it easier
to not have to readjust our build files each time a new file is added.
This means that files which are merely "included" cannot have a .c
suffix

Change-Id: I0ae076feea3f74ebb68bd99e3f76cae8ce09e0e2
Reviewed-on: http://review.couchbase.org/36223
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Brett Lawson <brett19@gmail.com>