Build failure due to @newStackCall being removed in 0.6.0

I found this neat little project today, and thought I should look into making it compile using `Zig 0.6.0`
> (Mainly as a fun challenge, since I do not yet know much about Zig)

### Making the following changes allows the code to build
`zig build-exe hellos.zig -target i386-freestanding --linker-script linker.ld`
```diff
diff --git a/hellos.zig b/hellos.zig
index 8563852..506f2c9 100644
--- a/hellos.zig
+++ b/hellos.zig
@@ -20,8 +20,9 @@ export var multiboot align(4) linksection(".multiboot") = MultiBoot{
export var stack_bytes: [16 * 1024]u8 align(16) linksection(".bss") = undefined;
const stack_bytes_slice = stack_bytes[0..];

-export nakedcc fn _start() noreturn {
- @newStackCall(stack_bytes_slice, kmain);
+export fn _start() callconv(.Naked) noreturn {
+ @call(.{ .stack = stack_bytes_slice }, kmain, .{});
+
while (true) {}
}

@@ -34,7 +35,7 @@ pub fn panic(msg: []const u8, error_return_trace: ?*builtin.StackTrace) noreturn

fn kmain() void {
terminal.initialize();
- terminal.write("Hello, kernel World!");
+ terminal.write("Hello, Kernel World from Zig 0.6.0!");
}

// Hardware text mode color constants
@@ -61,23 +62,26 @@ fn vga_entry_color(fg: VgaColor, bg: VgaColor) u8 {
}

fn vga_entry(uc: u8, color: u8) u16 {
- return u16(uc) | (u16(color) << 8);
+ var c: u16 = color;
+
+ return uc | (c << 8);
}

const VGA_WIDTH = 80;
const VGA_HEIGHT = 25;

const terminal = struct {
- var row = usize(0);
- var column = usize(0);
+ var row: usize = 0;
+ var column: usize = 0;
+
var color = vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);

const buffer = @intToPtr([*]volatile u16, 0xB8000);

fn initialize() void {
- var y = usize(0);
+ var y: usize = 0;
while (y < VGA_HEIGHT) : (y += 1) {
- var x = usize(0);
+ var x: usize = 0;
while (x < VGA_WIDTH) : (x += 1) {
putCharAt(' ', color, x, y);
}
```

### Screenshot


### Gist

https://gist.github.com/peterhellberg/e81128eae5adc6293d5c1bbeef3a3380