macros: fix compatibility with non-clang compilers
macros: fix compatibility with non-clang compilers

Signed-off-by: Frediano Ziglio <55d48b080b2e443e395cde84d2c83b135a4ff48e@redhat.com>

SPICE/spice-protocol,fgouget/spice-protocol,vdiot/spice-protocol,SPICE/spice-protocol,vdiot/spice-protocol,SPICE/spice-protocol,vdiot/spice-protocol,fgouget/spice-protocol,fgouget/spice-protocol