bitbake.conf/recipes: Introduce add DEV_PKG_DEPENDENCY to change RDEPENDS:${PN}-dev

There is a pattern that several recipes need to break the dependency of ${PN}-dev
on ${PN}, most often as ${PN} may be be empty. Add a new variable to parameterise
this and allow it to be changed more easily.

(From OE-Core rev: a5b381c0f45c590a762647a9956a8f41e2e2315e)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/conf/bitbake.conf

@@ -349,7 +349,8 @@ FILES:${PN}-dev = "${includedir} ${FILES_SOLIBSDEV} ${libdir}/*.la \
                 ${libdir}/cmake ${datadir}/cmake"
 SECTION:${PN}-dev = "devel"
 ALLOW_EMPTY:${PN}-dev = "1"
-RDEPENDS:${PN}-dev = "${PN} (= ${EXTENDPKGV})"
+DEV_PKG_DEPENDENCY = "${PN} (= ${EXTENDPKGV})"
+RDEPENDS:${PN}-dev = "${DEV_PKG_DEPENDENCY}"
 
 FILES:${PN}-staticdev = "${libdir}/*.a ${base_libdir}/*.a ${libdir}/${BPN}/*.a"
 SECTION:${PN}-staticdev = "devel"