patchsha1_file: Remove relative entries limitation

> link_alt_odb_entries() will be called recursively if alternates has
> valid object store paths, and to avoid nesting too deep, the
> recursive depth is limited to 5, this limitation is reasonable and
> safe for dead-loop reference situation.
>
> There is another limitation in this function to only permit the 1st
> level alternates has relative paths, but there is no foreseeable
> greater risk using relative paths in 2nd/3rd... level alternates than
> using absolute paths, in addition to we already have max depth 5
> limitation, we can safely remove this limitation.
>
> Moreover removing this limitation will make below two usage workable.
>
> usage1: base-repos has relative path in the alternates
>         %>git clone --reference base-repos src dest
> usage2: src2 has relative path to point src1, src1 has relative path
>     	to point src
>         %>git clone src2 dest
>
> Signed-off-by: Hui Wang <jason77.wang@gmail.com>
> ---
>  sha1_file.c |   13 ++++---------
>  1 files changed, 4 insertions(+), 9 deletions(-)
>
> diff --git a/sha1_file.c b/sha1_file.c
> index f7c3408..4130ca0 100644
> --- a/sha1_file.c
> +++ b/sha1_file.c
> @@ -332,15 +332,10 @@ static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
>  		}
>  		while (cp < ep && *cp != sep)
>  			cp++;
> -		if (last != cp) {
> -			if (!is_absolute_path(last) && depth) {
> -				error("%s: ignoring relative alternate object store %s",
> -						relative_base, last);
> -			} else {
> -				link_alt_odb_entry(last, cp - last,
> -						relative_base, depth);
> -			}
> -		}
> +		if (last != cp)
> +			link_alt_odb_entry(last, cp - last,
> +					relative_base, depth);
> +
>  		while (cp < ep && *cp == sep)
>  			cp++;
>  		last = cp;
>