[PATCH] -Werror fixes

GCC's format __attribute__ is good for checking errors, especially
with -Wformat=2 parameter. This fixes most of the reported problems
against 2005-08-09 snapshot.

pkt-line.h

@@ -5,7 +5,7 @@
  * Silly packetized line writing interface
  */
 void packet_flush(int fd);
-void packet_write(int fd, const char *fmt, ...);
+void packet_write(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
 
 int packet_read_line(int fd, char *buffer, unsigned size);