devtool / recipetool: support specifying a subdirectory within the fetched source
Sometimes you don't want to build an entire project, just a subdirectory
of it; add a --src-subdir option to make that easier. (We still look for
a single subdirectory in what gets unpacked, e.g. what you might find
within a tarball, so whatever you specify with this option is added onto
the end of that.)
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
