I am building kde5 on Ubuntu 14.04 32bit but it always fails to configure plasma-desktop with Cmake. This is the error message:
CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
X11_Xkbfile_LIB (ADVANCED)
linked by target "kcm_keyboard" in directory /Projects/kde5/kdesrc/plasma-desktop/kcms/keyboard
linked by target "kded_keyboard" in directory /Projects/kde5/kdesrc/plasma-desktop/kcms/keyboard
linked by target "xkb_rules_test" in directory /Projects/kde5/kdesrc/plasma-desktop/kcms/keyboard/tests
linked by target "iso_codes_test" in directory /Projects/kde5/kdesrc/plasma-desktop/kcms/keyboard/tests
linked by target "geometry_parser_test" in directory /Projects/kde5/kdesrc/plasma-desktop/kcms/keyboard/tests
linked by target "flags_test" in directory /Projects/kde5/kdesrc/plasma-desktop/kcms/keyboard/tests
linked by target "keyboard_daemon_test" in directory /Projects/kde5/kdesrc/plasma-desktop/kcms/keyboard/tests
Everything else is compiled, this is the only one with problems.
The error tells you that a cmake file cannot find a required library. The name X11_Xkbfile_LIB indicates that it should be one of the libraries that provide C bindings for X11 ("xkb"). Maybe installing libxcb-xkb-dev helps?