transformed {.reorder: on.} into {.experimental: codeReordering.}, added tests

tests/pragmas/treorder.nim

@@ -6,7 +6,8 @@ output:'''0
 """
 
 import macros
-{.reorder: on .}
+# {.reorder: on .}
+{.experimental: "codeReordering".}
 
 echo foo(-1)
 echo callWithFoo(0)
@@ -71,4 +72,4 @@ macro make(arg: untyped): untyped =
 proc first(i: int): void =
   make(second)
 
-var ss {.compileTime.}: string = ""
+var ss {.compileTime.}: string = ""

tests/pragmas/treorderdeclared.nim

@@ -0,0 +1,12 @@
+discard """
+output:'''false'''
+"""
+
+{.experimental: "codeReordering".}
+
+proc x() =
+  echo(declared(foo))
+
+var foo = 4
+
+x() # "false", the same as it would be with code reordering OFF