poppler: move RDEPENDS on poppler-data to libpoppler

The poppler-data package contains data needed by consumers of
the libpoppler package, for example evince.  However, the RDEPENDS in
this recipe is only for the poppler package.  Moving the RDEPENDS to
libpoppler ensures that poppler-data is included in any builds with
separate libpoppler consumers but not poppler.  The poppler package
automatically depends on libpoppler so poppler's dependency on
poppler-data is not lost.

Signed-off-by: Bob Ham <bob.ham@collabora.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>