libbluray: needs dynamic library support

The dependency is propagated to XBMC, even though XBMC currently
requires an (e)glibc toolchain, which always have dynamic library
support. This is just in case one day XBMC can be built against
uClibc.

Fixes:

  http://autobuild.buildroot.org/results/3fa/3fae35ebcf14d6f38284d8318f61f9b99998794c/



Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>