ASM extensions

[Walter Bright]

Georg Wrede wrote:
>> version blocks need to be syntactially valid code.  They're not like 
>> the C preprocessor's #if..#endif blocks.
>>
>> If one of these ASM syntaxes involves the use of curly braces, then 
>> finding the true end curly brace of the asm {} block itself might be 
>> difficult without understanding the ASM syntax itself.
> 
> Actually it wouldn't, because the curly braces in _any_ syntax come in 
> pairs. ;-)
> 
> But that fact alone doesn't help the real issue.

Their are some constraints on the asm syntax in order to support the D 
lexer and the version/debug statements.

But supporting the same CPU with multiple asm syntaxes just seems to be 
burdensome without much benefit.