[SourceKit] Adjust for LLVM StringRef change (swiftlang#29625)

StringRef needs an explicit conversion to std::string now.

Author: smeenai

tools/SourceKit/tools/sourcekitd/bin/InProc/sourcekitdInProc.cpp

@@ -93,7 +93,7 @@ std::string sourcekitd::getRuntimeLibPath() {
     llvm_unreachable("call to GetModuleFileNameA failed");
   libPath = llvm::sys::path::parent_path(llvm::sys::path::parent_path(path));
   llvm::sys::path::append(libPath, "lib");
-  return libPath.str();
+  return libPath.str().str();
 #else
   // This silly cast below avoids a C++ warning.
   Dl_info info;

tools/SourceKit/tools/sourcekitd/lib/API/sourcekitdAPI-InProc.cpp

@@ -633,7 +633,7 @@ void ResponseBuilder::Dictionary::set(UIdent Key, const char *Str) {
 
 void ResponseBuilder::Dictionary::set(UIdent Key, StringRef Str) {
   static_cast<SKDObject *>(Impl)->set(SKDUIDFromUIdent(Key), 
-                                      new SKDString(Str));
+                                      new SKDString(std::string(Str)));
 }
 
 void ResponseBuilder::Dictionary::set(UIdent Key, const std::string &Str) {
@@ -649,7 +649,7 @@ void ResponseBuilder::Dictionary::set(SourceKit::UIdent Key,
                                       ArrayRef<StringRef> Strs) {
   auto ArrayObject = new SKDArray();
   for (auto Str : Strs) {
-    ArrayObject->set(SOURCEKITD_ARRAY_APPEND, new SKDString(Str));
+    ArrayObject->set(SOURCEKITD_ARRAY_APPEND, new SKDString(std::string(Str)));
   }
   static_cast<SKDObject *>(Impl)->set(SKDUIDFromUIdent(Key), ArrayObject);
 }