When static_assert is a macro, it must have two arguments as seen by the
preprocessor. Add an identity mapping to the native case to enforce
this, and fix up all the sites that break with the new rule.
gcc-4.6 chokes on `static constexpr type value{};`, but accepts
`static constexpr auto value = type{};`
Fixes: 9595aec2fb ("Use integral_constant for endian constants")
Various functions use the non-macro form, so support for =delete is
already mandatory. Remove the remnants of support for compilers which
lack =delete and replace it with a hard stop when the compiler rejects
declaring explicitly deleted functions.
Clang warns for unused static inline functions defined in a source file,
including those defined in a macro in a header, when the macro is
expanded in the source file.
Add operator const void*() to prevent accidental use of pointer
comparison. With the overload present, comparing two objects triggers
an ambiguous conversion to pointer, instead of comparing the pointer
values.
