In selftest we want to exercise devtool's ability to use plugins from other
layers, so add a basic command to reverse a string to meta-selftest and a test
in oe-selftest to call it.
(From OE-Core rev: 69f5bbc1041e15691af0b4845e2136957a4846a1)
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>