bash: Update to 4.3.26

 * Fixes CVE-2014-7169.
 * Fix two out-of-bounds array accesses in the bash parser
 * Add prefix & suffix to variables containing exported functions

Ref: http://seclists.org/oss-sec/2014/q3/712

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>