Mostly preliminary clean-up in the hook API.
* ab/config-based-hooks-1:
hook-list.h: add a generated list of hooks, like config-list.h
hook.c users: use "hook_exists()" instead of "find_hook()"
hook.c: add a hook_exists() wrapper and use it in bugreport.c
hook.[ch]: move find_hook() from run-command.c to hook.c
Makefile: remove an out-of-date comment
Makefile: don't perform "mv $@+ $@" dance for $(GENERATED_H)
Makefile: stop hardcoding {command,config}-list.h
Makefile: mark "check" target as .PHONY
a5e61a4225