mcelog: remove bashism and create ptest subpackage

Create ptest subpackage. Add a patch to remove bashism and then only
ptest package depends on bash.

Inherit autotools-brokensep and re-write do_install as well.

Signed-off-by: Kai Kang <kai.kang@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>