config: correct '**' matching in includeIf patterns

The current wildmatch() call for includeIf's gitdir pattern does not pass the WM_PATHNAME flag. Without this flag, '*' is treated _almost_ the same as '**' (because '*' also matches slashes) with one exception: '/**/' can match a single slash. The pattern 'foo/**/bar' matches 'foo/bar'. But '/*/', which is essentially what wildmatch engine sees without WM_PATHNAME, has to match two slashes (and '*' matches nothing). Which means 'foo/*/bar' cannot match 'foo/bar'. It can only match 'foo//bar'. The result of this is the current wildmatch() call works most of the time until the user depends on '/**/' matching no path component. And also '*' matches slashes while it should not, but people probably haven't noticed this yet. The fix is straightforward. Reported-by: Jason Karns <jason.karns@gmail.com> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>