tests: Tweak cputest_LDADDS

tests: Tweak cputest_LDADDS

We want all test programs using qemu_LDADDS to also use LDADDS,
and cputest is the only existing exception.

We can't just replace GNULIB_LIBS with LDADDS though, even though
the latter is a superset of the former, because that would result
in a linking error due to including the same object twice:

  /usr/bin/ld:
  ../src/libvirt_probes.o:.../src/libvirt_probes.o.dtrace-temp.c:141:
  multiple definition of `libvirt_object_new_semaphore';
  ../src/libvirt_probes.o:.../src/libvirt_probes.o.dtrace-temp.c:141:
  first defined here

To work around this, we include both qemu_LDADDS and LDADDS when
QEMU support is enabled, and just LDADDS otherwise.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Jim Fehlig <jfehlig@suse.com>