Add #include <iostream> since Value.h does not include it any more.

llvm-svn: 14623
diff --git a/llvm/tools/llvm-as/llvm-as.cpp b/llvm/tools/llvm-as/llvm-as.cpp
index 9e9290d..eaa5a09 100644
--- a/llvm/tools/llvm-as/llvm-as.cpp
+++ b/llvm/tools/llvm-as/llvm-as.cpp
@@ -22,6 +22,7 @@
 #include "Support/CommandLine.h"
 #include "llvm/System/Signals.h"
 #include <fstream>
+#include <iostream>
 #include <memory>
 
 using namespace llvm;