Don't apply QM on lossless blocks

Similar to use of 'lossless' variable in setup_segmentation_dequant()
in libaom. Fixes #226 and #228.
14 jobs for master in 7 minutes and 38 seconds (queued for 23 seconds)
Status Job ID Name Coverage
  Style
passed #245105
amd64 debian
style-check

00:00:20

 
  Build
passed #245106
amd64 debian
build-debian

00:00:34

passed #245111
debian aarch64
build-debian-aarch64

00:01:29

passed #245112
debian aarch64
build-debian-aarch64-clang-5

00:01:08

passed #245107
amd64 debian
build-debian-static

00:00:32

passed #245114
debian aarch64
build-debian-werror

00:00:32

passed #245108
amd64 debian
build-debian32

00:00:25

passed #245113
macos
build-macos

00:00:48

passed #245109
win32
build-win32

00:00:28

passed #245110
win64
build-win64

00:00:34

 
  Test
passed #245115
amd64 debian
test-debian

00:00:46

passed #245116
amd64 debian
test-debian-asan

00:02:06

passed #245117
amd64 debian
test-debian-msan

00:01:02

passed #245118
amd64 debian
test-debian-ubsan

00:01:23