setting up nasm-compatible defines

[Peter Johnson]

On Thu, 8 Jun 2006, Mike Frysinger wrote:
> i was compiling some code originally written for nasm with yasm when i noticed
> that some code wasnt being included properly ... this is because a
> nasm-specific define was being used:
> %ifidn __OUTPUT_FORMAT__,elf

As yasm already had its own version of this (__YASM_OBJFMT__), this was 
really easy to support.  From an secondary cursory check it looks like 
yasm already supports all the other NASM defines are already supported 
(except of course for __NASM_VER* ones).

Committed support in r1557 (trunk) and r1558 (0.5.x branch).  It will be 
supported in the final 0.5.0 release.

Thanks,
Peter