chrpath.bbclass: Account for case when ORIGIN is in RPATH

chrpath.bbclass: Account for case when ORIGIN is in RPATH

This fixes a case when RPATH embedded in program have one of
its path already relative to ORIGIN. We were losing that path
if such a path existed. This patch appends it to the new edited
rpath being created when we see it.

so RPATH like below

(RPATH)              Library rpath:
[$ORIGIN/../lib/amd64/jli:$ORIGIN/../jre/lib/amd64/jli]

would end up being empty

but after this patch its kept intact

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>