Problem: MS-Windows: crash when passing long string to expand() with
'wildignorecase'.
Solution: Use the same buflen as unix_expandpath() in dos_expandpath().
Remove an unnecessary STRLEN() while at it (zeertzjq).
closes: vim/vim#1689600a749bd90
Problem: Code style is not check in test scripts.
Solution: Add basic code style check for test files.
94722c5107
Use Test_test_files() from latest Vim.
Co-authored-by: Bram Moolenaar <Bram@vim.org>