libsa: bootp is using pointers with different sign

Just change bp_file to char and same for variable s.

stand/libsa/bootp.c

@@ -735,7 +735,7 @@ setenv_(u_char *cp,  u_char *ep, struct dhcp_opt *opts)
 	    bcopy(cp, buf, size);	/* cannot overflow */
 	    buf[size] = '\0';
 	    for (endv = buf; endv; endv = vp) {
-		u_char *s = NULL;	/* semicolon ? */
+		char *s = NULL;	/* semicolon ? */
 
 		/* skip leading whitespace */
 		while (*endv && strchr(" \t\n\r", *endv))

stand/libsa/bootp.h

@@ -39,7 +39,7 @@ struct bootp {
 	struct in_addr	bp_giaddr;	/* gateway IP address */
 	unsigned char	bp_chaddr[16];	/* client hardware address */
 	unsigned char	bp_sname[64];	/* server host name */
-	unsigned char	bp_file[128];	/* boot file name */
+	char		bp_file[128];	/* boot file name */
 #ifdef SUPPORT_DHCP
 #define BOOTP_VENDSIZE 312
 #else