IDE: print underscored keywords for interface generation

Addressing @airspeedswift's code review feedback.

Author: nkcsgexi

include/swift/AST/PrintOptions.h

@@ -449,7 +449,6 @@ struct PrintOptions {
     result.ShouldQualifyNestedDeclarations =
         QualifyNestedDeclarations::Always;
     result.PrintDocumentationComments = true;
-    result.SkipUnderscoredKeywords = true;
     return result;
   }
 

lib/IDE/IDETypeChecking.cpp

@@ -77,6 +77,7 @@ PrintOptions PrintOptions::printDocInterface() {
   result.PrintDocumentationComments = false;
   result.PrintRegularClangComments = false;
   result.PrintFunctionRepresentationAttrs = false;
+  result.SkipUnderscoredKeywords = true;
   return result;
 }
 

test/IDE/print_type_interface.swift

@@ -71,15 +71,15 @@ extension D {
 // RUN: %target-swift-ide-test -print-type-interface -usr=_TtGSaSi_ -module-name print_type_interface -source-filename %s | %FileCheck %s -check-prefix=TYPE4
 // TYPE4-DAG: public typealias Index = Int
 // TYPE4-DAG: public func min() -> Int?
-// TYPE4-DAG: public mutating func insert<C>(contentsOf newElements: C, at i: Int)
+// TYPE4-DAG: public mutating func insert<C>(contentsOf newElements: __owned C, at i: Int)
 // TYPE4-DAG: public mutating func removeFirst(_ k: Int)
-// TYPE4-DAG: public func makeIterator() -> IndexingIterator<Array<Int>>
+// TYPE4-DAG: public __consuming func makeIterator() -> IndexingIterator<Array<Int>>
 // TYPE4-NOT: public func joined
 
 // RUN: %target-swift-ide-test -print-type-interface -usr=_TtGSaSS_ -module-name print_type_interface -source-filename %s | %FileCheck %s -check-prefix=TYPE5
-// TYPE5-DAG: public func prefix(_ maxLength: Int) -> ArraySlice<String>
-// TYPE5-DAG: public func suffix(_ maxLength: Int) -> ArraySlice<String>
-// TYPE5-DAG: public func split(separator: String, maxSplits: Int = Int.max, omittingEmptySubsequences: Bool = true) -> [ArraySlice<String>]
+// TYPE5-DAG: public __consuming func prefix(_ maxLength: Int) -> ArraySlice<String>
+// TYPE5-DAG: public __consuming func suffix(_ maxLength: Int) -> ArraySlice<String>
+// TYPE5-DAG: public __consuming func split(separator: String, maxSplits: Int = Int.max, omittingEmptySubsequences: Bool = true) -> [ArraySlice<String>]
 // TYPE5-DAG: public func formIndex(_ i: inout Int, offsetBy distance: Int)
 // TYPE5-DAG: public func distance(from start: Int, to end: Int) -> Int
 // TYPE5-DAG: public func joined(separator: String = "") -> String