Migrate to newer API.

Following function (left) is deprecated, use the right version
instead:

llvm::sys::Path::getLast     -> llvm::sys::path::filename
llvm::sys::Path::getBasename -> llvm::sys::path::stem
llvm::sys::Path::getDirname  -> llvm::sys::path::parent_path
diff --git a/llvm-rs-cc.cpp b/llvm-rs-cc.cpp
index 4eadfea..e22ae1e 100644
--- a/llvm-rs-cc.cpp
+++ b/llvm-rs-cc.cpp
@@ -331,8 +331,7 @@
   ExpandArgv(argc, argv, ArgVector, SavedStrings);
 
   // Argv0
-  llvm::sys::Path Path = llvm::sys::Path(ArgVector[0]);
-  Argv0 = Path.getBasename();
+  Argv0 = llvm::sys::path::stem(ArgVector[0]);
 
   // Setup diagnostic engine
   clang::TextDiagnosticPrinter *DiagClient =
diff --git a/slang.cpp b/slang.cpp
index 02e7e45..bc73e4d 100644
--- a/slang.cpp
+++ b/slang.cpp
@@ -121,10 +121,8 @@
   slangAssert((OutputFile != NULL) && (Error != NULL) && (Diag != NULL) &&
               "Invalid parameter!");
 
-  llvm::sys::Path OutputFilePath(OutputFile);
-
-  if (SlangUtils::CreateDirectoryWithParents(OutputFilePath.getDirname(),
-                                             Error)) {
+  if (SlangUtils::CreateDirectoryWithParents(
+                        llvm::sys::path::parent_path(OutputFile), Error)) {
     llvm::tool_output_file *F =
           new llvm::tool_output_file(OutputFile, *Error, Flags);
     if (F != NULL)
diff --git a/slang_rs.cpp b/slang_rs.cpp
index c5aadff..7945f95 100644
--- a/slang_rs.cpp
+++ b/slang_rs.cpp
@@ -232,9 +232,8 @@
                                        const clang::SourceManager &SourceMgr) {
   clang::FullSourceLoc FSL(FD->getLocStart(), SourceMgr);
   clang::PresumedLoc PLoc = SourceMgr.getPresumedLoc(FSL);
-  llvm::sys::Path HeaderFilename(PLoc.getFilename());
 
-  return IsRSHeaderFile(HeaderFilename.getLast().data());
+  return IsRSHeaderFile(llvm::sys::path::filename(PLoc.getFilename()).data());
 }
 
 SlangRS::SlangRS() : Slang(), mRSContext(NULL), mAllowRSPrefix(false) {