gotwebd: plug two memory leak and drop unneeded ternary ok tracey@

don't leak memory allocated internally by bloom filters; ok jamsek

tog: remove gcc ternary if extension ok stsp@

add a gotwebd todo item

remove gotwebd TODO items that are done

gotwebd: drop the x bit from assets in-tree and also when installing ok stsp@

wrap overlong line in diff.sh

fix NULL deref in the object cache debug code; ok stsp@ it's not in code compiled by default as it's under GOT_OBJ_CACHE_DEBUG.

fix dup(2) error checking in got_gotweb_openfile()

in got_operations.c, remove error variables which were only used to return NULL

get rid of (null) on the index page. ok stsp

keep track of the size of the largest object which entered an object cache

mark check_refcount as static needed because of -Wmissig-prototypes; ok stsp@

object cache: if kicking an object out to make space, reuse its mem allocation

update gotwebd.8 httpd.conf example snippet based on feedback by op@