CMake: Make sure to detect LibXml2 when Clang is built standalone

llvm-svn: 170444
GitOrigin-RevId: 4d65bbd50948c1b10467ede3ea805f438f44f262
diff --git a/CMakeLists.txt b/CMakeLists.txt
index f7099ac..0ad0557 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -66,6 +66,11 @@
   set( CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib )
 
   set( CLANG_BUILT_STANDALONE 1 )
+
+  find_package(LibXml2)
+  if (LIBXML2_FOUND)
+    set(CLANG_HAVE_LIBXML 1)
+  endif ()
 endif()
 
 set(CLANG_RESOURCE_DIR "" CACHE STRING