CxxUtils: Try to bundle common checks together

CxxUtils: Try to bundle common checks together

This should go after @ssnyder takes a look.

A copy of the code with #warning added to help in compiler explorer

• https://godbolt.org/z/qK443cWGf (gcc 11 x86)
• https://godbolt.org/z/jbdTTW1Kj (clang 14 x86)
• https://godbolt.org/z/1EYj89qfx (gcc11 ARM64)