binutils: fix symlinks

binutils: fix symlinks

For nativesdk, symlinks created by do_install contain ${SDKPATHNATIVE}.

This is a problem with SDKs that include nativesdk-binutils and nativesdk-gcc.
When extracting such an SDK dangling symlinks are created, because
relocate_sdk.py does not adjust symlinks. As a result gcc ends up calling the
host binutils.

Use the os.path.relpath function to obtain shorter relative paths, which do not
contain ${SDKPATHNATIVE}.

(From OE-Core rev: 3d6372aa2d9f752eac0e4943d1bde04f0f1924a0)

Signed-off-by: Achille Fouilleul <achille.fouilleul@gadz.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>