[compiler] 128-bit arguments and return values

[water111]

The compiler should support 128-bit values in argument and return registers.

By default, the compiler should use the type to determine if an argument/return should be passed in an xmm or a gpr. This will work in all cases we've seen so far, but you could imagine for example a function pointer with type (function object object) that is sometimes called with a 128-bit argument and sometimes not, and sometimes the function being called uses 128-bit arguments and sometimes not. If this ends up happening, we'll have to manually annotate these functions.

Functions should be able to use some declare form to pick xmm/gpr for each argument/return value.
There should be a call form added that allows a function call by pointer and overrides xmm/gpr for each argument/return value.

[water111]

Things to remember to test:

• inline functions
• methods
• immediate lambda
• bitfield inspects

[water111]

added in #510