gallium/u_threaded: skip draws if user index buffer size has size == 0

This happens when all draws have count == 0.

Fixes: 85b6ba13 "st/mesa: implement Driver.DrawGallium callbacks

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <!8345>
73 jobs for !8345 with draw-interface-fixes in 17 minutes and 24 seconds (queued for 3 seconds)
detached
Status Job ID Name Coverage
  Sanity
passed #6552549
sanity

00:00:08

 
  Container
passed #6552552
aarch64
arm_build

00:00:19

passed #6552553
arm_test-base

00:00:12

passed #6552554
windows shell 1809 mesa
windows_build_vs2019

00:00:19

passed #6552550
x86_build-base

00:00:13

passed #6552551
x86_test-base

00:00:13

 
  Container 2
passed #6552562
android_build

00:00:16

passed #6552565
arm64_test

00:00:15

passed #6552566
armhf_test

00:00:15

passed #6552559
i386_build

00:00:19

passed #6552555
kernel+rootfs_amd64

00:00:19

passed #6552556
aarch64
kernel+rootfs_arm64

00:01:09

passed #6552557
aarch64
kernel+rootfs_armhf

00:00:16

passed #6552560
ppc64el_build

00:00:16

passed #6552561
s390x_build

00:00:11

passed #6552558
x86_build

00:00:15

passed #6552563
x86_test-gl

00:00:11

passed #6552564
x86_test-vk

00:00:16

 
  Meson X86 64
passed #6552572
meson-clang

00:03:42

passed #6552573
meson-clover

00:01:49

passed #6552569
meson-clover-testing

00:01:22

passed #6552570
meson-gallium

00:03:23

passed #6552571
meson-release

00:01:26

passed #6552567
meson-testing

00:02:13

passed #6552568
meson-testing-asan

00:04:40

passed #6552574
meson-vulkan

00:01:31

 
  Build Misc
passed #6552575
meson-android

00:01:21

passed #6552577
aarch64
meson-arm64

00:03:07

passed #6552578
aarch64
meson-arm64-build-test

00:03:16

passed #6552576
aarch64
meson-armhf

00:03:31

passed #6552581
meson-i386

00:02:45

passed #6552584
meson-mingw32-x86_64

00:03:04

passed #6552583
kvm
meson-ppc64el

00:03:05

passed #6552582
kvm
meson-s390x

00:03:52

passed #6552579
windows docker 1809 mesa
meson-windows-vs2019

00:04:04

passed #6552580
scons-win64

00:04:49

 
  Amd
passed #6552585
mesa-ci-aarch64-lava-collabora
radeonsi-stoney-gles2:amd64

00:06:58

passed #6552587
mesa-ci-aarch64-lava-collabora
radeonsi-stoney-gles31:amd64

00:09:06

passed #6552586
mesa-ci-aarch64-lava-collabora
radeonsi-stoney-gles3:amd64

00:14:31

passed #6552588
mesa-ci-aarch64-lava-collabora
radeonsi-stoney-traces:amd64

00:06:45

passed #6552589
radv-fossils

00:08:58

 
  Arm
passed #6552595
mesa-ci-aarch64-lava-collabora
panfrost-g52-gles2:arm64

00:03:47

passed #6552590
mesa-ci-aarch64-lava-collabora
panfrost-t720-gles2:arm64

00:07:41

passed #6552591
mesa-ci-aarch64-lava-collabora
panfrost-t860-gles2:arm64

00:04:18

passed #6552592
mesa-ci-aarch64-lava-collabora
panfrost-t860-gles3:arm64 1/2

00:06:18

passed #6552593
mesa-ci-aarch64-lava-collabora
panfrost-t860-gles3:arm64 2/2

00:06:07

passed #6552594
mesa-ci-aarch64-lava-collabora
panfrost-t860-traces:arm64

00:07:40

 
  Raspberrypi
passed #6552596
igalia-rpi3
vc4-rpi3-gles2:armhf 1/4

00:05:14

passed #6552597
igalia-rpi3
vc4-rpi3-gles2:armhf 2/4

00:04:46

passed #6552598
igalia-rpi3
vc4-rpi3-gles2:armhf 3/4

00:05:38

passed #6552599
igalia-rpi3
vc4-rpi3-gles2:armhf 4/4

00:05:23

 
  Software Renderer
passed #6552612
lavapipe-vk

00:07:40

passed #6552605
llvmpipe-gles2

00:00:58

passed #6552600
llvmpipe-piglit-cl

00:01:59

passed #6552602
llvmpipe-piglit-glslparser

00:02:55

passed #6552601
llvmpipe-piglit-quick_gl

00:06:14

passed #6552603
llvmpipe-piglit-quick_shader

00:05:54

passed #6552604
llvmpipe-traces

00:01:48

passed #6552611
softpipe-gl

00:00:59

passed #6552606
softpipe-gles2

00:01:42

passed #6552607
softpipe-gles3

00:05:26

passed #6552608
softpipe-gles31 1/2

00:05:14

passed #6552609
softpipe-gles31 2/2

00:05:07

passed #6552610
softpipe-piglit-quick

00:03:10

 
  Layered Backends
passed #6552613
windows docker 1809 mesa
test-d3d12-windows

00:03:48

passed #6552619
virgl-gl30-on-gl

00:00:28

passed #6552620
virgl-gl31-on-gl

00:00:50

passed #6552621
virgl-gl32-on-gl

00:01:41

passed #6552615
virgl-gles2-on-gl

00:02:19

passed #6552617
virgl-gles31-on-gl 1/2

00:04:13

passed #6552618
virgl-gles31-on-gl 2/2

00:04:31

passed #6552616
virgl-gles3-on-gl

00:02:15

passed #6552614
virgl-traces

00:00:50