Looks like gtk-doc.make is meant for automake, not make.
Some previous changes need to be reverted.
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
In 29a00c41 an override was added, but commandline variables have
higher precedence than Makefile variables, so the override was not
effective for commandline variables.
While at it, duplicate for libudev.
gtk-doc add CFLAGS/LDFLAGS multiple times to the gcc command line,
which breaks options that must be listed only once.
For now, clear CFLAGS/LDFLAGS for the intermediate documentation
binary.
Anthony G. Basile