Prepare larger packet buffer for upload-pack protocol.

The original side-band support added to the upload-pack protocol used the
default 1000-byte packet length.  The pkt-line format allows up to 64k, so
prepare the receiver for the maximum size, and have the uploader and
downloader negotiate if larger packet length is allowed.

Signed-off-by: Junio C Hamano <junkio@cox.net>

sideband.h

@@ -5,6 +5,7 @@
 #define SIDEBAND_REMOTE_ERROR -1
 
 #define DEFAULT_PACKET_MAX 1000
+#define LARGE_PACKET_MAX 65520
 
 int recv_sideband(const char *me, int in_stream, int out, int err, char *, int);
 ssize_t send_sideband(int fd, int band, const char *data, ssize_t sz, int packet_max);