update/project/trees: remove extra.sh handling

This functionality has never been used, except in the
erstwhile osboot project, and even then only experimentally.

It was intended for use with coreboot's gerrit site, but
it became Libreboot project policy that this not be relied
upon, instead preferring to include patches directly within
lbmk. This functionality can be re-added, if necessary.

Signed-off-by: Leah Rowe <leah@libreboot.org>

script/update/project/trees

@@ -157,13 +157,6 @@ prepare_new_tree()
 			err "cannot patch: ${project}/${tree}"
 		fi
 	done
-
-	# extra.sh can be used for anything
-	# but should *only* be a last resort
-	if [ -f "../../${cfgsdir}/${tree}/extra.sh" ]; then
-		"../../${cfgsdir}/${tree}/extra.sh" || \
-		    err "prepare_new_tree ${project}/${tree}: extra.sh: error"
-	fi
 	)
 }