vim-patch:9.1.1517: filetype: autopkgtest files are not recognized

Problem:  filetype: autopkgtest files are not recognized
Solution: detect */debian/tests/control files as autopkgtest filetype
          (James McCoy)

Autopkgtest is a Debian tool for testing installed versions of packages
when other, related packages are updated.

Reference:
- https://www.debian.org/doc/debian-policy/autopkgtest.txt

related: vim/vim#17679

5bcc492649

Co-authored-by: James McCoy <jamessan@jamessan.com>

test/old/testdir/test_filetype.vim

@@ -126,6 +126,7 @@ func s:GetFilenameChecks() abort
     \ 'autohotkey': ['file.ahk'],
     \ 'autoit': ['file.au3'],
     \ 'automake': ['GNUmakefile.am', 'makefile.am', 'Makefile.am'],
+    \ 'autopkgtest': ['/debian/tests/control', 'any/debian/tests/control'],
     \ 'ave': ['file.ave'],
     \ 'awk': ['file.awk', 'file.gawk'],
     \ 'b': ['file.mch', 'file.ref', 'file.imp'],