Replace #import with #include to please VC++.

VC++ chokes on the #import, and thinks we are trying to import
libraries. Replace by #include, which should be more portable.

Author: drodriguez

lib/ClangImporter/ClangSourceBufferImporter.cpp

@@ -10,10 +10,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-#import "ClangSourceBufferImporter.h"
-#import "swift/Basic/SourceManager.h"
-#import "clang/Basic/SourceManager.h"
-#import "llvm/Support/MemoryBuffer.h"
+#include "ClangSourceBufferImporter.h"
+#include "swift/Basic/SourceManager.h"
+#include "clang/Basic/SourceManager.h"
+#include "llvm/Support/MemoryBuffer.h"
 
 using namespace swift;
 using namespace swift::importer;