Add plugin loading for clang. This will be used to load alternative constraint manager for static analysis.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@60091 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/Driver/clang.cpp b/Driver/clang.cpp
index ead8734..dacdca7 100644
--- a/Driver/clang.cpp
+++ b/Driver/clang.cpp
@@ -47,6 +47,7 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/PluginLoader.h"
 #include "llvm/System/Host.h"
 #include "llvm/System/Path.h"
 #include "llvm/System/Signals.h"