* tests/testutilsqemu.c: add a machine types list for /usr/bin/kvm
  which doesn't have any aliases, while the guest has aliases

* tests/qemuxml2argvdata/qemuxml2argv-machine-aliases2.*,
  tests/qemuxml2argvtest.c: add a test using /usr/bin/kvm and make
  sure that 'pc' machine type doesn't get canonicalized using the
  aliases in the guest machine type list