[SILParser] fix a few issues to enable parsing of sil from swift array

Add PrintForSIL in PrintOptions
1> for NameAliasType, we print getSinglyDesugaredType()
I attempted another option: set FullyQualifiedTypes of PrintOptions, but that
will print xxx.Type.xxx and Parser can’t handle it.
2> for Self, we print @sil_self

We also work around parsing:
sil_witness_table _CocoaArrayType: _CocoaArrayType

sil_vtable uses internal classes in stdlib, so we use lookupTopDecl instead
of lookupValue when parsing sil_vtable, to find internal classes.

Fix rdar://17261925 rdar://17295316 rdar://17046276 rdar://17579890


Swift SVN r20070

include/swift/AST/PrintOptions.h

@@ -105,6 +105,9 @@ struct PrintOptions {
   /// Whether to print accessibility information on all value decls.
   bool PrintAccessibility = false;
 
+  /// Whether we are printing for sil.
+  bool PrintForSIL = false;
+
   enum class ArgAndParamPrintingMode {
     ArgumentOnly,
     BothIfDifferent,