autotools: Exclude variables from autotools_copy_aclocals

The autotools aclocal copy function should not depend on various variables, these
are accounted for in other parts of the system. Therefore exclude them.

This was causing differences in sstate checksums between different systems and meaning
the sstate cache wasn't being reused as much as it should.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
pixbufcache: Fix librsvg-native build

bitbake librsvg-native would fail with an error about missing icu-native.
The reason is that bitbake doesn't directly parse setscene dependencies. This
change ensures bitbake does see the dependencies and avoids the error.

Ideally we'd teach bitbake about those but that is a significant and complex
change so this resolves the problem for now.

[YOCTO #5926]

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