scripts: Bugfix compile error on chinese system.

The command "bash --version" output "Version 4.x", but in a chinese
locale system will display as "版本 4.x".

Signed-off-by: Guo Ren <ren_guo@c-sky.com>

scripts/prereq.sh

@@ -225,7 +225,7 @@ printf " --->  checking if bash is installed.. "
 if which bash >/dev/null; then
   printf "found\n"
   printf " --->  checking if it is bash 4.x.. "
-  bash --version 2>/dev/null| grep -i "Version 4" >/dev/null
+  bash --version 2>/dev/null| grep "GNU bash" | grep -i " 4." >/dev/null
   if [ $? -eq 0 ]; then
     printf "yes\n"
   else