where is this LINALG_ENABLE_KOKKOS_DEFAULT set?

[fnrizzi]

@crtrott @mhoemmen

I was trying to build using Kokkos, using this cmake line:
when I configure, I use:

    cmake \
	-Dmdspan_DIR=${MDSPAN_PFX}/lib/cmake/mdspan \
	-DLINALG_ENABLE_TESTS=On \
	-DLINALG_ENABLE_EXAMPLES=On \
	-DCMAKE_BUILD_TYPE="${btype}" \
	\
	-DLINALG_ENABLE_KOKKOS=On \
	-DKokkos_DIR=${KOKKOS_DIR} \
	-DKokkosKernels_DIR=${KOKKOS_KER_DIR} \
	\
	-DCMAKE_VERBOSE_MAKEFILE=On \
	-DCMAKE_INSTALL_PREFIX=../stdblas-install \
	-DGTEST_ROOT=../install_gtest \
	../stdBLAS/

But that causes a problem, because in this file: linalg_execpolicy_mapper.hpp we have:

#if defined(LINALG_ENABLE_KOKKOS) && defined(LINALG_ENABLE_KOKKOS_DEFAULT)
#include <experimental/__p1673_bits/kokkos-kernels/exec_policy_wrapper_kk.hpp>
#endif

and since LINALG_ENABLE_KOKKOS_DEFAULT is NOT set at all, I get a compile error because that header is not included.
If I change that to || it works.

But was wondering: what is the role of LINALG_ENABLE_KOKKOS_DEFAULT? Is that supposed to be set by user? Or what?