utils/getdeveloperlib.py: call Developer.hasfile() with relative path
In commit
40bb37bd70d46822e803aaa5169dee8ff8b51093 ("utils/getdeveloperlib.py:
use relative paths for files"), the Developer class was changed to use
relative paths, including for its .hasfile() method.
However the check_developers() function of getdeveloperlib.py was not
updated accordingly, and continued to pass absolute paths. This caused
"get-developers -c" to return the entire list of files in Buildroot as
being unmaintained, as none of them were matching the file listed in
the DEVELOPERS file.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>