pan/bi: Add a trivial ctx->inputs for unit tests

So we can unit test the flow control insertion which needs to gate some
behaviour on not being in a blend shader.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16804>

src/panfrost/bifrost/bi_test.h

@@ -38,6 +38,7 @@ bit_builder(void *memctx)
         bi_context *ctx = rzalloc(memctx, bi_context);
         list_inithead(&ctx->blocks);
         ctx->num_blocks = 1;
+        ctx->inputs = rzalloc(memctx, struct panfrost_compile_inputs);
 
         bi_block *blk = rzalloc(ctx, bi_block);