Rewrite with working async

lib/rt/jsrt.h

@@ -3,13 +3,16 @@
 //
 // Each header declares its part, and if JSRT_IMPLEMENTATION is defined before
 // this is included, also defines it. The emitted C is one file, which does
-// that, and includes this before any other header. The natives are declared
-// by the emitted C itself, from compiler/src/native.rs, and defined here
+// that, and includes this before any other header
 //
-// core.h     values, the object header, the allocator, errors
-// str.h      strings and the string natives
-// number.h   the number natives
-// any.h      any_t and JS's operators on it
+// The fns that the program can call have one of two prefixes:
+// __rt_*      the same on every platform: JS's operators, strings, numbers,
+//             the allocator and errors
+// __native_*  the platform's IO, which another platform's runtime replaces
+//
+// core.h     values, the allocator, errors
+// str.h      strings
+// number.h   numbers, and their conversions to and from strings
 // io.h       IO natives, async on io_uring (uring.h), and the host's loop
 //
 // The host owns the event loop. The program exports two fns, which the host
@@ -36,5 +39,4 @@ void jsrt_complete(int32_t h);
 
 #include "str.h"
 #include "number.h"
-#include "any.h"
 #include "io.h"