Sema: incorrectly simplifies comptime zero divided by runtime float

[jacobly0]

const std = @import("std");
const nan = std.math.nan;
var rt_nan: @Vector(1, f32) = .{nan(f32)};
var rt_zero: @Vector(1, f32) = .{0};
const ct_zero: @Vector(1, f32) = .{0};
pub fn main() void {
    std.debug.print("{} {}\n", .{ @divTrunc(rt_zero, rt_nan), @divTrunc(ct_zero, rt_nan) });
    std.debug.print("{} {}\n", .{ @divFloor(rt_zero, rt_nan), @divFloor(ct_zero, rt_nan) });
}

$ zig run repro.zig
{ nan } { 0e0 }
{ nan } { 0e0 }

As an added bonus for fixing this bug, you can delete the lines in test/behavior/x86_64/math.zig referencing this issue!