fix: kacess should not be built if xkb is not present
Review Request #126013 - Created Nov. 10, 2015 and submitted
The XCB-XKB dependency of plasma-desktop is optional, however kacess depends directly and unconditionally on the xcb/xkb.h header file. This causes the build of plasma-desktop to fail at compile stage if the xkb header is not present. As per the convention in the kcm modules shipped by plasma-desktop, inclusion of the kacess subdirectory is made conditional on XKB being present and properly detected during the cmake configure stage.
Built without xkb header, using kdesrc-build