gitlab-ci: drop most autotools builds

With autotools this close to being not supported anymore, let's not
waste half of the CI cycles on it. The default build will catch most
issues, and the rest can be tested by the old Travis.

Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
15 jobs for !414 with gitlab-ci-drop-autotools in 50 minutes and 3 seconds (queued for 57 minutes and 19 seconds)
detached
Status Job ID Name Coverage
  Containers Build
passed #181354
ubuntu

00:00:42

 
  Build+Test
passed #181365
autotools

00:17:34

passed #181358
meson-clang

00:08:20

passed #181362
meson-gallium-clover-llvm

00:03:18

passed #181363
meson-gallium-clover-llvm39

00:03:40

passed #181361
meson-gallium-drivers-other

00:04:58

passed #181360
meson-gallium-radeonsi

00:04:40

passed #181364
meson-gallium-st-other

00:03:07

passed #181359
meson-gallium-swr

00:10:10

passed #181357
meson-glvnd

00:05:12

passed #181356
meson-loader-classic-dri

00:06:39

passed #181355
meson-vulkan

00:03:37

passed #181367
scons-llvm

00:06:15

passed #181366
scons-nollvm

00:04:51

passed #181368
scons-swr

00:06:40