aalib_1.4p5.orig.tar.gz: convert to Git LFS

The .orig.tar.xz got accidentally committed as a plain file in contrast to what is set in .gitattributes, making git lfs fsck very unhappy:

$ git checkout pristine-lfs
$ git lfs fsck
pointer: unexpectedGitObject: "aalib_1.4p5.orig.tar.gz" (treeish
4b80cb5841acb0bbcc2ba16c8339024a3b3c1b0e) should have been a pointer
but was not

Re-import the files as LFS objects to make LFS happy again:

$ git lfs migrate import --no-rewrite aalib_1.4p5.orig.tar.gz
migrate: checkout: ..., done.
$ git lfs fsck
Git LFS fsck OK