linux-kbuild: Fix cross-build regression

The upstream resolve_btfids Makefile tries to always do a native build, so it requires the same workaround as objtool to cross-build it while still building fixdep natively. The initial addition of this tool to linux-kbuild was missing the variables needed to build fixdep correctly.

Additionally, resolve_btfids builds libbpf, which builds fixdep in its own way. Add a patch to make it use the standard fixdep build rule.

Fixes: edab15ab ("Install resolve_btfid tool")