* Move NodeCollector into package collector
* Refactor collector enabling
* Update README with new collector enabled flags
* Fix out-of-date inline flag reference syntax
* Use new flags in end-to-end tests
* Add flag to disable all default collectors
* Track if a flag has been set explicitly
* Add --collectors.disable-defaults to README
* Revert disable-defaults flag
* Shorten flags
* Fixup timex collector registration
* Fix end-to-end tests
* Change procfs and sysfs path flags
* Fix review comments
The devstat API expects us to reuse one devinfo for many invocations of
devstat_getstats. In particular, it allocates and resizes memory
referenced by devinfo.
Querying the number of devices separately from the device list itself is
racy. Devices may be added or removed between the two calls; and removed
devices would lead to a segfault.
The memory allocated by calloc was never freed. Since the devinfo struct
never leaves the function, anyway, we might as well just allocate it on
the stack.
