Fixes #5167 and related problems (#5475)

This commit returns to a bit less strict checking of the number
of macro arguments, because some old immediate macros rely on a
behavior where even the arity of the macro is not being checked.

It may be better if such macros are just declared to use varargs[expr],
but this remains for another day.

tests/macros/tmacro4.nim

@@ -5,7 +5,7 @@ discard """
 import
   macros, strutils
 
-macro test_macro*(n: stmt): stmt {.immediate.} =
+macro test_macro*(s: string, n: stmt): stmt {.immediate.} =
   result = newNimNode(nnkStmtList)
   var ass : NimNode = newNimNode(nnkAsgn)
   add(ass, newIdentNode("str"))