cleanup Ordinal (#13501)

tests/system/tsystem_misc.nim

@@ -193,3 +193,20 @@ block:
     a = {k1}
     b = {k1,k2}
   doAssert a < b
+
+
+block: # Ordinal
+  doAssert int is Ordinal
+  doAssert uint is Ordinal
+  doAssert int64 is Ordinal
+  doAssert uint64 is Ordinal
+  doAssert char is Ordinal
+  type Foo = enum k1, k2
+  doAssert Foo is Ordinal
+  doAssert Foo is SomeOrdinal
+  doAssert enum is SomeOrdinal
+
+  # these fail:
+  # doAssert enum is Ordinal # fails
+  # doAssert Ordinal is SomeOrdinal
+  # doAssert SomeOrdinal is Ordinal

tests/varres/tprevent_forloopvar_mutations.nim

@@ -3,9 +3,9 @@ discard """
   line: 17
   nimout: '''type mismatch: got <int>
 but expected one of:
-proc inc[T: Ordinal | uint | uint64](x: var T; y = 1)
+proc inc[T: Ordinal](x: var T; y = 1)
   first type mismatch at position: 1
-  required type for x: var T: Ordinal or uint or uint64
+  required type for x: var T: Ordinal
   but expression 'i' is immutable, not 'var'
 
 expression: inc i