Speeds up the build.

xilinx_ethlite uses tswap32() and is thus target-dependent.
Signed-off-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NEdgar E. Iglesias <edgar.iglesias@gmail.com>

This completes the move to nested Makefiles for virtio and a few
other files that were not part of obj-TARGET-y, but still were
compiled separately for each target.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

After this patch, the libhw* directories will have a hierarchy
that mimics the source tree.  This is useful because we do have
a couple of files there that are in the top source directory.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

This patch starts converting the hw/ directory.  Some files in hw/
are compiled once, some twice (32-/64-bit), some once per target.
Each category is moved in a separate patch.

After this patch, the files that are compiled once will show the
same hierarchy in the build tree as they do in the source tree,
for example hw/qdev.o instead of just qdev.o.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>