dtc: broken for static builds

dtc package has hardcoded shared lib link options in the Makefile, so it
will fail if you try to build it on a static lib environment.

[Peter: Move comment under _PROGRAMS suboption for proper indentation]
Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>