Fix printf errors.

The compiler will help find mismatches between printf formats and
arguments if you let it.  This patch adds the necessary attributes to
declarations in include/common.h, then begins to correct the resulting
compiler warnings.  Some of these were bugs, e.g., "$d" instead of
"%d" and incorrect arguments.  Others were just annoying, like
int-long mismatches on a system where both are 32 bits.  It's worth
fixing the annoying errors to catch the real ones.

Signed-off-by: Andrew Klossner <andrew@cesa.opbu.xerox.com>

net/tftp.c

@@ -178,7 +178,7 @@ TftpSend (void)
 		pkt += 5 /*strlen("octet")*/ + 1;
 		strcpy ((char *)pkt, "timeout");
 		pkt += 7 /*strlen("timeout")*/ + 1;
-		sprintf((char *)pkt, "%d", TIMEOUT);
+		sprintf((char *)pkt, "%lu", TIMEOUT);
 #ifdef ET_DEBUG
 		printf("send option \"timeout %s\"\n", (char *)pkt);
 #endif