* Add DUK_BSWAP64() fill-in when 64-bit types available.
* Add DUK_BSWAP16(), DUK_BSWAP32(), and DUK_BSWAP64() GCC and Clang
built-ins. These are nice but unnecessary except at low optimizations
because the macros compile down to proper bswap instructions.
* Improve bswap self tests.
Replaced #ifdefs with DUK_U64_CONSTANT and DUK_I64_CONSTANT macros for cleaner
code and to prevent future breakage, as suggested by svaarala.
Missed a few replacements. Added.
Last one.
Changed parameter name from x to a.
Split MinGW and MSVC typedefs for 64-bit types.
Added myself to list of code contributors.