clarify comment

unpack_repack_bin.sh

@@ -450,7 +450,7 @@ enable_gdb()
         else
             log "Using recent ASA gdb patching method"
             sed -i 's/#\(.*\)ttyUSB0\(.*\)/\1ttyS0\2/' asa/scripts/rcS
-            # Don't output anything on the tty, as this breaks some gdb versions
+            # Don't output anything on the tty, as this breaks gdb with some Linux kernel setups
             sed -i 's/ttyS0::once:\/tmp\/run_cmd/tty0::once:\/tmp\/run_cmd/' etc/inittab
         fi
     fi