test: add mtd/ubi test helpers

I used these to develop the mtd/ubi ioctl decoders.

* test/.gitignore: Add mtd/ubi.
* test/Makefile: Declare all tests in a PROGS var.
Declare build targets .PHONY.
(all): Depend on $(PROGS) instead of hardcoded list.
(clean): Remove $(PROGS) instead of hardcoded list.
* test/mtd.c: New file.
* test/ubi.c: Likewise.
4 files changed