sthttpd: add recipe

This is the "supported" fork of thttpd which has a rewritten build
system to avoid the need to patch it, as well as other minor
fixes. The recipe was based on the thttpd recipe in meta-arago-extras
(originally migrated from OE-Classic by
Franklin S. Cooper Jr <fcooper@ti.com>) with the following improvements:

* Set SUMMARY
* Remove PARALLEL_MAKE = "" (new build system should avoid previous issues)
* Use more accurate LICENSE
* Rearrange recipe to conform with current style
* Use += instead of _append for FILES definitions
* Add LSB headers to initscript
* Fix hardcoded ${sbindir} in initscript

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>