mesa: add support for CET to x86/x86-64 asm files.

Control-flow enforcement technology is a new instructions on x86
processors to denote where indirect jumps can land. Gcc auto adds
the instruction (which encodes as a NOP on older CPUs) to entrypoints
but assembler files need manual adding. This adds it to all the
entry points in the mesa x86/x86-64 assembler files.

This will only happen if mesa is built with the -fcf-protection flag
to gcc as some distros are wanting to do.

Acked-by: Eric Anholt <eric@anholt.net>
17 jobs for !1621 with mesa-cet-support in 16 minutes and 28 seconds (queued for 2 seconds)
detached
Status Job ID Name Coverage
  Containers Build
passed #509138
debian

00:00:22

 
  Build+Test
passed #509147
meson-arm64

00:02:15

passed #509146
meson-armhf

00:03:00

passed #509140
meson-clang

00:10:28

passed #509144
meson-clover

00:11:26

passed #509148
meson-i386

00:03:13

passed #509143
meson-main

00:12:02

passed #509139
meson-swr-glvnd

00:07:36

passed #509145
meson-vulkan

00:02:18

passed #509150
scons-llvm

00:02:32

passed #509149
scons-nollvm

00:02:40

passed #509141
scons-swr

00:07:43

passed #509142
scons-win64

00:10:20

 
  Test
passed #509151
test-llvmpipe-gles2 1/4

00:02:17

passed #509152
test-llvmpipe-gles2 2/4

00:02:28

passed #509153
test-llvmpipe-gles2 3/4

00:03:57

passed #509154
test-llvmpipe-gles2 4/4

00:02:44