set $logfile before use

Originally committed as revision 13178 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1060,6 +1060,11 @@ for opt do
     esac
 done
 
+disabled logging && logfile=/dev/null
+
+echo "# $0 $@" > $logfile
+set >> $logfile
+
 cc="${cross_prefix}${cc}"
 ar="${cross_prefix}${ar}"
 nm="${cross_prefix}${nm}"
@@ -1307,11 +1312,6 @@ esac
 
 add_extralibs $osextralibs
 
-disabled logging && logfile=/dev/null
-
-echo "# $0 $@" > $logfile
-set >> $logfile
-
 # Combine FFLDFLAGS and the LDFLAGS environment variable.
 LDFLAGS="$FFLDFLAGS $LDFLAGS"