util: rename list_empty() to list_is_empty()

This makes it clear that it's a boolean test and not an action
(eg. "empty the list").

Reviewed-by: Eric Engestrom <eric@engestrom.ch>

src/broadcom/compiler/nir_to_vir.c

@@ -429,7 +429,7 @@ ntq_store_dest(struct v3d_compile *c, nir_dest *dest, int chan,
                struct qreg result)
 {
         struct qinst *last_inst = NULL;
-        if (!list_empty(&c->cur_block->instructions))
+        if (!list_is_empty(&c->cur_block->instructions))
                 last_inst = (struct qinst *)c->cur_block->instructions.prev;
 
         assert((result.file == QFILE_TEMP &&