Driver: IWYU swift-symbolgraph-extract

This is needed to build on swift/master-rebranch.

tools/driver/swift_symbolgraph_extract_main.cpp

@@ -23,6 +23,7 @@
 #include "swift/SymbolGraphGen/SymbolGraphGen.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/CommandLine.h"
 
 using namespace swift;
 using namespace llvm::opt;