SIGSEGV on comptime_int used as inline assembly input operand

[tiehuis]

pub fn main() void {
    const in = 5;
    var out: u32 = 0;

    const r = asm ("movl %%eax, %%ebx"
        : [out] "={ebx}" (-> u32)
        : [eax] "{eax}" (in)
    );

    @import("std").debug.assert(r == in);
}

Crashes with:

fish: “zig build-exe t.zig” terminated by signal SIGSEGV (Address boundary error)

Explicitly specifying the input operand width fixes the issue:

const in: u32 = 5;

Should suffice to omit a compile error on comptime_int given as a parameter. I know there is a lot of changes and improvements to the inline assembly system wanted anyway, so this isn't too important and can be left until #215 is decided.

[tiehuis]

Just saw that this is a duplicate of #728.