Add bitsizeof to Builtins (#2376)

* Add `bitsizeof` to Builtins

---------

Co-authored-by: Christoffer Lerno <christoffer@aegik.com>

lib/std/core/builtin.c3

@@ -89,6 +89,10 @@ macro void @swap(#a, #b) @builtin
 	#b = temp;
 }
 
+macro usz bitsizeof($Type) @builtin @const => $Type.sizeof * 8u;
+
+macro usz @bitsizeof(#expr) @builtin @const => $sizeof(#expr) * 8u;
+
 <*
  Convert an `any` type to a type, returning an failure if there is a type mismatch.