move ExtWeakSymbols to AsmPrinter

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@32648 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/AsmPrinter.h

@@ -18,6 +18,7 @@
 
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/Support/DataTypes.h"
+#include <set>
 
 namespace llvm {
   class Constant;
@@ -39,6 +40,10 @@ namespace llvm {
     ///
     unsigned FunctionNumber;
 
+  protected:
+    // Necessary for external weak linkage support
+    std::set<const GlobalValue*> ExtWeakSymbols;
+
   public:
     /// Output stream on which we're printing assembly code.
     ///