shader: add some strbuf error checks.

We definitely want to check for errors after each instruction
and after iteration and header generation.

This should allow the explicit checks to be removed now.

Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/vrend_shader.c

@@ -4014,6 +4014,8 @@ iter_instruction(struct tgsi_iterate_context *iter,
       snprintf(buf, 255, "%s = clamp(%s, 0.0, 1.0);\n", dsts[0], dsts[0]);
       EMIT_BUF_WITH_RET(ctx, buf);
    }
+   if (strbuf_get_error(&ctx->glsl_main))
+       return false;
    return true;
 }
 
@@ -5062,14 +5064,21 @@ char *vrend_convert_shader(struct vrend_context *rctx,
    if (bret == false)
       goto fail;
 
+   if (strbuf_get_error(&ctx.glsl_main))
+      goto fail;
+
    if (!strbuf_alloc(&ctx.glsl_hdr, 1024))
       goto fail;
+
    if (!emit_header(&ctx))
       goto fail;
 
    if (!emit_ios(&ctx))
       goto fail;
 
+   if (strbuf_get_error(&ctx.glsl_hdr))
+      goto fail;
+
    glsl_final = malloc(strbuf_get_len(&ctx.glsl_hdr) + strbuf_get_len(&ctx.glsl_main) + 1);
    if (!glsl_final)
       goto fail;