Add snapcraft packaging

.gitignore

@@ -5,3 +5,4 @@
 tags
 .DS_Store
 /tests/dav1d-test-data
+*.snap

snap/snapcraft.yaml

+name: dav1d
+base: core18
+version: git
+summary: AV1 decoder from VideoLAN
+description: |
+  A small and fast AV1 decoder from the people who brought you VLC.
+
+grade: devel # must be 'stable' to release into candidate/stable channels
+confinement: strict # use 'strict' once you have the right plugs and slots
+
+apps:
+  dav1d:
+    command: usr/bin/dav1d
+    plugs: [ 'home' ]
+
+parts:
+  dav1d:
+    plugin: meson
+    source: .
+    build-packages: [ 'nasm' ]
+    meson-parameters:
+      - --prefix=/usr
+      - --buildtype=release