.gitignore: Remove autotool artifacts

Signed-off-by: Kristian H. Kristensen <hoegsberg@google.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
14 jobs for !688 with gitignore-cleanup in 11 minutes and 54 seconds (queued for 1 second)
latest detached
Status Job ID Name Coverage
  Containers Build
passed #247504
debian

00:00:18

 
  Build+Test
passed #247506
meson-clang

00:11:34

passed #247512
meson-gallium-clover-llvm

00:03:13

passed #247513
meson-gallium-clover-llvm39

00:02:43

passed #247511
meson-gallium-drivers-other

00:08:03

passed #247510
meson-gallium-radeonsi

00:05:48

passed #247514
meson-gallium-st-other

00:02:47

passed #247505
meson-gallium-swr

00:10:18

passed #247509
meson-glvnd

00:03:40

passed #247508
meson-loader-classic-dri

00:04:45

passed #247507
meson-vulkan

00:01:39

passed #247516
scons-llvm

00:05:23

passed #247515
scons-nollvm

00:02:30

passed #247517
scons-swr

00:05:17