Currently compiler yells at `printmimo()` with the following warning:
```
/usr/home/melifaro/free/head/sbin/ifconfig/ifieee80211.c:3716:17: error: comparison of array 'mi->ch[i].rssi' not equal to a null pointer is always true [-Werror,-Wtautological-pointer-compare]
if (mi->ch[i].rssi != 0) {
~~~~~~~~~~^~~~ ~
```
To check:
```
--- a/sbin/ifconfig/Makefile
+++ b/sbin/ifconfig/Makefile
@@ -80,7 +80,8 @@ CFLAGS+=-DWITHOUT_NETLINK
MAN= ifconfig.8
CFLAGS+= -Wall -Wmissing-prototypes -Wcast-qual -Wwrite-strings -Wnested-externs
-WARNS?= 2
+CFLAGS+=-Wno-error=unused-parameter -Wno-error=shadow
+#WARNS?= 2
```
I have no domain knowledge whether the fix is valid or not, but the code before 617f8b101e7f checked `rssi[0]`.