libxkbcommon: Add missing dependency on xkeyboard-config

libxkbcommon depends on xkeyboard-config

Signed-off-by: Mikhail Durnev <mikhail_durnev@mentor.com>
Merge pull request #102 from mdurnev/mdurnev/libxkbcommon

libxkbcommon: Add missing dependency on xkeyboard-config