Add a recipetool subcommand "setvar" to set a variable in a file. This
uses our existing logic such that it doesn't matter if the variable is
already set in the recipe, if it's set in the recipe or some inc file,
and if the variable is not currently set that the line setting the
variable gets inserted in the right place in the file.
Implements [YOCTO #7676].
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
