Fix setting PAX options for crossgen (#13950)

Fix setting PAX options for crossgen (#13950)

In my previous PR that added marking executables with paxctl, I've made
a mistake in the order of calling _add_library and add_dependencies.
But that was hidden due to the fact that we have yet another copy of the
add_library_clr and add_executable_clr functions in src/CMakeLists.txt.
I have no idea how that happened.
This one has overriden the other, which has hidden the problem, but also
caused the crossgen to not to be modified by the paxctl.
So I am fixing the order and removing the extra definitions of those
functions.