So we can avoid using using an attribute not supported for the compiler.
warning:
../spice-common/common/mem.h:91:80: warning: unknown attribute
'__alloc_size__' ignored [-Wunknown-attributes]
void *spice_malloc0_n(size_t n_blocks, size_t n_block_bytes)
SPICE_GNUC_MALLOC SPICE_GNUC_ALLOC_SIZE2(1,2);
../spice-common/spice-protocol/spice/macros.h:52:52: note: expanded
from macro 'SPICE_GNUC_ALLOC_SIZE2'
#define SPICE_GNUC_ALLOC_SIZE2(x,y) __attribute__((__alloc_size__(x,y)))
^
fa19ebb83f