meta-oe: stop using "virtual/" in RPROVIDES and RDEPENDS

Recipes shouldn't use the "virtual/" string in RPROVIDES and RDEPENDS.

That's confusing because "virtual/" has no special meaning in
RPROVIDES and RDEPENDS (unlike in PROVIDES and DEPENDS).

Instead, using "virtual-" instead of "virtual/"
as already done in the glibc recipe in OE-core

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>