[NFC] Add comments with SR numbers for language version mode changes

Author: beccadax

lib/Parse/ParseExpr.cpp

@@ -1022,7 +1022,7 @@ static MagicIdentifierLiteralExpr::Kind
 getMagicIdentifierLiteralKind(tok Kind, const LangOptions &Opts) {
   switch (Kind) {
   case tok::pound_file:
-    // TODO: Enable by default at the next source break.
+    // TODO: Enable by default at the next source break. (SR-13199)
     return Opts.EnableConcisePoundFile
          ? MagicIdentifierLiteralExpr::FileIDSpelledAsFile
          : MagicIdentifierLiteralExpr::FilePathSpelledAsFile;

test/SILGen/magic_identifier_file.swift

@@ -21,6 +21,8 @@
 // Test in "Swift 6" mode:
 // RUN: %target-swift-emit-silgen -I %t -enable-experimental-concise-pound-file -module-name Foo %/s | %FileCheck --check-prefixes=BOTH,CONCISE %s
 
+// TODO: Update RUN lines currently using -enable-experimental-concise-pound-file to use -swift-version <whatever> instead. (SR-13199)
+
 import MagicIdentifierFileSwift5
 import MagicIdentifierFileSwift6