Backport of "meson: d3d11: Disable library build if DirectXMath header was not found" into 1.24
Backport of !6468 (merged) "meson: d3d11: Disable library build if DirectXMath header was not found".
Commits:
- d0cfada1 meson: d3d11: Disable library build if DirectXMath header was not found