* codegen: LLVMConstInlineAsm is deprecated.

* codegen: replace commas in asm constraint strings by pipes as required by LLVM.

* ir: enforce usage of '=' constraint modifier for inline assembly outputs.

Others are not currently supported and this was just asserted alter in `ir_render_asm`.

* asm: forbid comptime_int/floats as inputs in favor of explicitely sized constants.

Fixes a crash due to comptime_int/floats having no type_ref.

* asm: handle inputs with integers of <8 or non power of 2 bitsize.

We widen them to the next highest power of two.