gitweb: "alternate" starts with shade (i.e. 1)

gitweb: "alternate" starts with shade (i.e. 1)

When displaying a list of rows (difftree, shortlog, etc),
the first entry is now printed shaded, i.e. alternate is
initialized to 1, as opposed to non-shaded (alternate
initialized to 0).

This solves the problem when there is only one row to
display -- it is displayed shaded to visually indicate that
it is "active", part of a "list", etc.

(Compare this to the trivial case of more than one entry,
where the rows have alternating shade, thus suggesting
being part of a "list" of "active" entries, etc.)

Signed-off-by: Luben Tuikov <redacted>
Signed-off-by: Junio C Hamano <redacted>