Revert "[script] ..why detect gtk twice"

This reverts commit 4138a52ea879cd13c5c453f1dcec672fe547e242.
[cmake] use CMAKE_CURRENT_LIST_FILE instead of CMAKE_CURRENT_LIST_DIR in order to support old cmake versions
[gtk,qt,ipc] compatible with old qt and dbus
[cmake] ..cmake 2.6, die in peace.
[qt] add option to disable gui part
[fcitx] fix compatible with gcc 4.6