py: Allow viper to have type annotations.

Viper functions can now be annotated with the type of their arguments
and return value.  Eg:

@micropython.viper
def f(x:int) -> int:
    return x + 1

py/qstrdefs.h

@@ -67,9 +67,13 @@ Q(__lt__)
 
 Q(micropython)
 Q(bytecode)
+Q(const)
+
+#if MICROPY_EMIT_X64 || MICROPY_EMIT_THUMB
 Q(native)
 Q(viper)
-Q(const)
+Q(uint)
+#endif
 
 #if MICROPY_EMIT_INLINE_THUMB
 Q(asm_thumb)