configure: replace 'pr' with printf since busybox does not support pr

This patch is based on https://trac.ffmpeg.org/ticket/5680 provided by
Kylie McClain <somasis@exherbo.org> at Wed, 29 Jun 2016 16:37:20 -0400,
and have some changes.

contributor: Kylie McClain <somasis@exherbo.org>
contributor: avih <avihpit@yahoo.com>
Signed-off-by: Guo, Yejun <yejun.guo@intel.com>

configure

@@ -503,9 +503,13 @@ log(){
 }
 
 log_file(){
-    log BEGIN $1
-    pr -n -t $1 >> $logfile
-    log END $1
+    log BEGIN "$1"
+    log_file_i=1
+    while IFS= read -r log_file_line; do
+        printf '%5d\t%s\n' "$log_file_i" "$log_file_line"
+        log_file_i=$(($log_file_i+1))
+    done < "$1" >> "$logfile"
+    log END "$1"
 }
 
 warn(){