busybox: enable ash getopts

It's increasingly used by scripts like some in the btrfs-progs package.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/busybox/busybox.config

@@ -975,7 +975,7 @@ CONFIG_ASH_BASH_COMPAT=y
 CONFIG_ASH_IDLE_TIMEOUT=y
 CONFIG_ASH_JOB_CONTROL=y
 CONFIG_ASH_ALIAS=y
-# CONFIG_ASH_GETOPTS is not set
+CONFIG_ASH_GETOPTS=y
 CONFIG_ASH_BUILTIN_ECHO=y
 CONFIG_ASH_BUILTIN_PRINTF=y
 CONFIG_ASH_BUILTIN_TEST=y