And move the MAP_ANON redefinition from py/asmx64.c to unix/alloc.c.

Fixes issue #840

It defines types used by all other headers.

Fixes #691.

Blanket wide to all .c and .h files.  Some files originating from ST are
difficult to deal with (license wise) so it was left out of those.

Also merged modpyb.h, modos.h, modstm.h and modtime.h in stmhal/.

Native emitter has been broken since stack order has changed from
reverse to standard.  This fix gets it partially working.

With MICROPY_EMIT_X64 and MICROPY_EMIT_THUMB disabled, the respective
emitters and assemblers will not be included in the code.  This can
significantly reduce binary size for unix version.