decode: add a frame tile data buffer size check

This check was already done in dav1d_parse_obus(), so it's added as an assert
here for extra precaution.
21 jobs for master in 6 minutes and 41 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Style
passed #265191
amd64 debian
style-check

00:00:23

 
  Build
passed #265192
amd64 debian
build-debian

00:00:38

passed #265200
debian aarch64
build-debian-aarch64

00:01:33

passed #265201
debian aarch64
build-debian-aarch64-clang-5

00:01:10

passed #265204
debian armv7
build-debian-armv7

00:02:47

passed #265205
debian armv7
build-debian-armv7-clang-5

00:01:14

passed #265193
amd64 debian
build-debian-static

00:00:38

passed #265203
debian aarch64
build-debian-werror

00:00:34

passed #265194
amd64 debian
build-debian32

00:00:33

passed #265202
macos
build-macos

00:00:35

passed #265206
amd64 debian allowed to fail
build-ubuntu-snap

00:01:07

passed #265198
amd64 debian
build-win-arm32

00:00:31

passed #265199
amd64 debian
build-win-arm64

00:00:34

passed #265195
amd64 debian
build-win32

00:00:41

passed #265196
amd64 debian
build-win32-unaligned-stack

00:00:38

passed #265197
amd64 debian
build-win64

00:00:47

 
  Test
passed #265207
amd64 debian
test-debian

00:00:46

passed #265208
amd64 debian
test-debian-asan

00:02:14

passed #265209
amd64 debian
test-debian-msan

00:01:09

passed #265210
amd64 debian
test-debian-ubsan

00:01:31

passed #265211
amd64 debian
test-win64

00:00:47