tWe need err.h in all cases, assume we have it - spoon - dwm status utility (2f30 fork)
 (HTM) git clone git://src.adamsgaard.dk/spoon
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       ---
 (DIR) commit fea90b396a2dae46ac53edc6d09df12be614727c
 (DIR) parent 969ca7f8b748dc1a14d35bc8c906864e6ef771f6
 (HTM) Author: lostd <lostd@2f30.org>
       Date:   Wed, 12 Oct 2016 23:22:12 +0100
       
       We need err.h in all cases, assume we have it
       
       Diffstat:
         M batt.c                              |       2 +-
         M wifi.c                              |       2 +-
       
       2 files changed, 2 insertions(+), 2 deletions(-)
       ---
 (DIR) diff --git a/batt.c b/batt.c
       t@@ -1,3 +1,4 @@
       +#include <err.h>
        #include <stddef.h>
        #include <stdio.h>
        
       t@@ -24,7 +25,6 @@ battprint(char *buf, size_t len, int acon , int life)
        #ifdef __OpenBSD__
        #include <sys/ioctl.h>
        
       -#include <err.h>
        #include <fcntl.h>
        #include <unistd.h>
        
 (DIR) diff --git a/wifi.c b/wifi.c
       t@@ -1,3 +1,4 @@
       +#include <err.h>
        #include <stddef.h>
        #include <stdio.h>
        
       t@@ -29,7 +30,6 @@ wifiprint(char *buf, size_t len, int quality)
        #include <net80211/ieee80211.h>
        #include <net80211/ieee80211_ioctl.h>
        
       -#include <err.h>
        #include <ifaddrs.h>
        #include <string.h>
        #include <unistd.h>