[clang-tidy] Fix llvm-include-order check on Windows.

IncludeDirectives struct used a StringRef that pointed to a stack variable
(SmallString<128> FilenameBuffer from PPDirectives.cpp:1513).

http://reviews.llvm.org/D12632

Patch by Marek Kurdej!

llvm-svn: 246856
diff --git a/clang-tools-extra/clang-tidy/llvm/IncludeOrderCheck.cpp b/clang-tools-extra/clang-tidy/llvm/IncludeOrderCheck.cpp
index b5064da..e6d5bc3 100644
--- a/clang-tools-extra/clang-tidy/llvm/IncludeOrderCheck.cpp
+++ b/clang-tools-extra/clang-tidy/llvm/IncludeOrderCheck.cpp
@@ -33,7 +33,7 @@
   struct IncludeDirective {
     SourceLocation Loc;    ///< '#' location in the include directive
     CharSourceRange Range; ///< SourceRange for the file name
-    StringRef Filename;    ///< Filename as a string
+    std::string Filename;  ///< Filename as a string
     bool IsAngled;         ///< true if this was an include with angle brackets
     bool IsMainModule;     ///< true if this was the first include in a file
   };
diff --git a/clang-tools-extra/test/clang-tidy/llvm-include-order.cpp b/clang-tools-extra/test/clang-tidy/llvm-include-order.cpp
index 5d97817..b1b8c34 100644
--- a/clang-tools-extra/test/clang-tidy/llvm-include-order.cpp
+++ b/clang-tools-extra/test/clang-tidy/llvm-include-order.cpp
@@ -1,7 +1,6 @@
 // RUN: %python %S/check_clang_tidy.py %s llvm-include-order %t -- -isystem %S/Inputs/Headers
 
 // FIXME: Investigating.
-// XFAIL: win32
 
 // CHECK-MESSAGES: [[@LINE+2]]:1: warning: #includes are not sorted properly
 #include "j.h"