eol: improve hook failure output Before, only the first failure was reported: abort: b.txt should not have CRLF line endings while now all of them are listed: abort: end-of-line check failed: d.txt in a7040e68714f should not have CRLF line endings b.txt in fbcf9b1025f5 should not have CRLF line endings As first suggested by Antoine Pitrou <solipsis@pitrou.net>