elementary: add eio to DEPENDS

* fixes:
| /bin/grep: /OE/shr-core/tmp-eglibc/sysroots/spitz/usr/lib/libeio.la: No such file or directory
| /bin/sed: can't read /OE/shr-core/tmp-eglibc/sysroots/spitz/usr/lib/libeio.la: No such file or directory
| arm-oe-linux-gnueabi-libtool: link: `/OE/shr-core/tmp-eglibc/sysroots/spitz/usr/lib/libeio.la' is not a valid libtool archive
| make[3]: *** [module.la] Error 1
| make[3]: Leaving directory `/OE/shr-core/tmp-eglibc/work/armv5te-oe-linux-gnueabi/elementary-2_1.0.1+svnr74527-r1.0/elementary/src/edje_externals'

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>