Add back a form of parseIntoSourceFile for LLDB.

This is a temporary shim.

Author: DougGregor

include/swift/Subsystems.h

@@ -119,6 +119,17 @@ namespace swift {
                            PersistentParserState *PersistentState = nullptr,
                            bool DelayBodyParsing = true);
 
+  /// DEPRECATED: Only used to break LLDB/Swift dependency.
+  inline
+  bool parseIntoSourceFile(SourceFile &SF, unsigned BufferID, bool *Done,
+                           SILParserState *SIL,
+                           PersistentParserState *PersistentState,
+                           std::nullptr_t,
+                           bool DelayBodyParsing) {
+    return parseIntoSourceFile(SF, BufferID, Done, SIL, PersistentState,
+                               DelayBodyParsing);
+  }
+
   /// Parse a single buffer into the given source file, until the full source
   /// contents are parsed.
   ///