fix enumtostr crash for enum-range (#13035)

compiler/ccgexprs.nim

@@ -2070,7 +2070,7 @@ proc genDispose(p: BProc; n: PNode) =
 
 proc genEnumToStr(p: BProc, e: PNode, d: var TLoc) =
   const ToStringProcSlot = -4
-  let t = e[1].typ.skipTypes(abstractInst)
+  let t = e[1].typ.skipTypes(abstractInst+{tyRange})
   var toStrProc: PSym = nil
   for idx, p in items(t.methods):
     if idx == ToStringProcSlot:

tests/enum/tenum_no_rtti.nim

@@ -0,0 +1,12 @@
+discard """
+  output: '''A
+B'''
+  cmd: '''nim c --gc:arc $file'''
+"""
+type
+  Enum = enum A, B, C
+  EnumRange = range[A .. B]
+proc test_a(x: Enum): string = $x
+proc test_b(x: EnumRange): string = $x
+echo test_a(A)
+echo test_b(B)