Snippets for flatpak 1.18.1 from Alpine armv7

Sourced from https://build.alpinelinux.org/buildlogs/build-edge-armv7/community/flatpak/flatpak-1.18.1-r0.log.

• ../common/flatpak-prune.c:655:6: warning: 'exists' may be used uninitialized [-Wmaybe-uninitialized]
    655 |   if (!exists)
        |      ^
  

• ../common/flatpak-oci-registry.c:2224:16: warning: 'size' may be used uninitialized [-Wmaybe-uninitialized]
   2224 |           if (!g_seekable_seek (G_SEEKABLE (content_file), size, G_SEEK_SET, cancellable, error))
        |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~