obey_variables() was using relative paths which mean it depends on exactly what
directory it starts in. To clarify the code, always use absolute paths.
(From OE-Core rev: 74b1757e080d14188fe9f77f6e07ed83b696a2c8)
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>