[Orc] fixes "streams.readDataStr segafaults" when accepting a string literal (#20019) [backport]

fixes streams.readDataStr accept a string literal

(cherry picked from commit 286fcef68e)

tests/stdlib/tstreams.nim

@@ -85,3 +85,13 @@ block:
 static: # Ensure streams it doesnt break with nimscript on arc/orc #19716
   let s = newStringStream("a")
   doAssert s.data == "a"
+
+template main =
+  var strm = newStringStream("abcde")
+  var buffer = "12345"
+  doAssert strm.readDataStr(buffer, 0..3) == 4
+  doAssert buffer == "abcd5"
+  strm.close()
+
+static: main()
+main()