16bit code generation

[Tijl Coosemans]

I was reading through binutils documentation and came across this.
Maybe it can be used to compile 16 bit tests.

3.2.4. 16-bit mode
Binutils (2.9.1.0.25+) now fully support 16-bit mode (registers and
addressing) on i386 PCs. Use .code16 and .code32 to switch between
assembly modes.

Also, a neat trick used by several people (including the oskit authors)
is to force GCC to produce code for 16-bit real mode, using an inline
assembly statement asm(".code16\n"). GCC will still emit only 32-bit
addressing modes, but GAS will insert proper 32-bit prefixes for them.