[packages] xmail: fix endianness detection

 * fix endianness detection (closes: #9913)
 * bump release number

git-svn-id: svn://svn.openwrt.org/openwrt/packages@36236 3c298f89-4303-0410-b956-a3cf2f4a3e73
Merge branch 'prop-updates' of github.com:psycho-nico/openwrt-packages into prop-updates