Zig workaround: don't use packed structs larger than 128 bits.

The C backend currently can't handle them

src/Diagnostics.zig

@@ -73,7 +73,8 @@ pub const Tag = std.meta.DeclEnum(messages);
 // u4 to avoid any possible packed struct issues
 pub const Kind = enum(u4) { @"fatal error", @"error", note, warning, off, default };
 
-pub const Options = packed struct {
+/// TODO: make this `packed struct` once the C backend can handle packed structs larger than 128 bits
+pub const Options = struct {
     // do not directly use these, instead add `const NAME = true;`
     all: Kind = .default,
     extra: Kind = .default,

src/object/Elf.zig

@@ -20,7 +20,7 @@ const Symbol = struct {
     info: u8,
 };
 
-const Relocation = packed struct {
+const Relocation = struct {
     symbol: *Symbol,
     addend: i64,
     offset: u48,