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@

remove trailing whitespace; patch by Josiah Frentsos

gotwebd: use SCRIPT_NAME to derive URLs This makes gotwebd use SCRIPT_NAME instead of the DOCUMENT_ROOT fastcgi param to generate the links to the assets and changes some links so every page is consistently linked with a relative URL. It allows to drop the `root "/"' in the location for fastcgi and, as a bonus, also makes possible to run gotwebd on non "/" paths. ok stsp@

gotwebd: garbage collect %token FCGI_SOCKET ok stsp@

remove fcgi_socket keyword from gotwebd.conf; "listen on" now implies it ok op@

got: fix typo in argc check when diffing two blobs We already have two arguments when diffing two blobs, so check for more than two like we do when diffing two objects to check for invalid path args. Includes new regress test by op for diffing two blobs. ok stsp@ and ok plus regress test from op@