Fix compiler warning from sysctl.c

[Ashton Fagg]

Fixes the following warning:

sysctl.c:835:18: warning: format specifies type 'char *' but the argument has 
type 'void *' [-Wformat]
                                            string, newval);
                                                    ^~~~~~
sysctl.c:840:18: warning: format specifies type 'char *' but the argument has 
type 'void *' [-Wformat]
                                            string, newval);

Appears as though this was fixed in lines above these two instances, but
these were still not properly cast.


diff --git a/sbin/sysctl/sysctl.c b/sbin/sysctl/sysctl.c
index 5e9e562d308..a03220d7d56 100644
--- a/sbin/sysctl/sysctl.c
+++ b/sbin/sysctl/sysctl.c
@@ -832,12 +832,12 @@ parse(char *string, int flags)
 				    newval);
 				if (len == -1) {
 					warnx("%s: hex string %s: invalid",
-					    string, newval);
+					    string, (char *)newval);
 					return;
 				}
 				if (len > sizeof(hex)) {
 					warnx("%s: hex string %s: too long",
-					    string, newval);
+					    string, (char *)newval);
 					return;
 				}