VERSION_GREATER_EQUAL was introduced in cmake 3.7, but the specified minimum version is 3.0.
So use NOT VERSION_LESS instead to still support older cmake versions too.

Builds fine with cmake 3.5.2 now, and also newer versions.
The file is still installed to ${KDE_INSTALL_LOGGINGCATEGORIESDIR} when building with latest KF5 from git, haven't tried older versions.

Before, I got this error when using cmake 3.5.2:

CMake Error at CMakeLists.txt:153 (if):
  if given arguments:

    "ECM_VERSION" "VERSION_GREATER_EQUAL" "5.59.0"

  Unknown arguments specified