anv: Use a read-write lock for the pipeline cache

This should reduce contention with hot caches.  I have no performance
numbers for it though.
40 jobs for !3821 with wip/anv-pipeline-cache-rwlock in 22 minutes and 9 seconds (queued for 3 seconds)
latest detached
Status Job ID Name Coverage
  Container
passed #1627149
aarch64
arm_build

00:00:26

passed #1627150
aarch64
arm_test

00:00:25

passed #1627146
x86_build

00:00:25

passed #1627148
x86_build_old

00:00:21

passed #1627147
x86_test-gl

00:00:20

 
  Build
passed #1627154
aarch64
meson-arm64

00:11:19

passed #1627153
aarch64
meson-armhf

00:10:41

passed #1627155
meson-clang

00:06:39

passed #1627158
meson-clover

00:06:09

passed #1627159
meson-clover-old-llvm

00:06:40

passed #1627161
meson-i386

00:03:07

passed #1627152
meson-main

00:06:25

passed #1627164
meson-mingw32-x86_64

00:05:02

passed #1627163
gstreamer
meson-ppc64el

00:03:41

passed #1627162
gstreamer
meson-s390x

00:04:22

passed #1627151
meson-testing

00:04:47

passed #1627160
meson-vulkan

00:04:46

passed #1627165
scons

00:04:18

passed #1627166
scons-old-llvm

00:04:43

passed #1627156
scons-swr

00:05:13

passed #1627157
scons-win64

00:06:29

 
  Test
passed #1627185
db410c
arm64_a306_gles2

00:06:25

passed #1627182
mesa-cheza
arm64_a630_gles2

00:03:19

passed #1627184
mesa-cheza
arm64_a630_gles3

00:09:13

passed #1627183
mesa-cheza
arm64_a630_gles31

00:06:51

passed #1627170
lava-meson-gxl-s905x-libretech-cc
lima-mali450-test:arm64

00:10:13

passed #1627167
lava-sun50i-h6-pine-h64
panfrost-t720-test:arm64

00:07:48

passed #1627168
lava-rk3288-veyron-jaq
panfrost-t760-test:armhf

00:05:30

passed #1627169
lava-rk3399-gru-kevin
panfrost-t860-test:arm64

00:09:17

passed #1627172
piglit-glslparser

00:04:04

passed #1627171
piglit-quick_gl

00:07:28

passed #1627173
piglit-quick_shader

00:05:48

passed #1627174
test-llvmpipe-gles2

00:03:57

passed #1627175
test-softpipe-gles2

00:01:37

passed #1627178
test-softpipe-gles31 1/4

00:02:50

passed #1627176
test-softpipe-gles3 1/2

00:04:58

passed #1627179
test-softpipe-gles31 2/4

00:04:00

passed #1627180
test-softpipe-gles31 3/4

00:04:51

passed #1627181
test-softpipe-gles31 4/4

00:03:16

passed #1627177
test-softpipe-gles3 2/2

00:04:26