Fixed MSVC unresolved symbol error due to an incorrectly declared extern

llvm-svn: 274007
diff --git a/llvm/lib/CodeGen/MachineBlockFrequencyInfo.cpp b/llvm/lib/CodeGen/MachineBlockFrequencyInfo.cpp
index 4353ec4..6c0f99f 100644
--- a/llvm/lib/CodeGen/MachineBlockFrequencyInfo.cpp
+++ b/llvm/lib/CodeGen/MachineBlockFrequencyInfo.cpp
@@ -47,7 +47,7 @@
                clEnumValEnd));
 
 extern cl::opt<std::string> ViewBlockFreqFuncName;
-extern cl::opt<uint64_t> ViewHotFreqPercent;
+extern cl::opt<unsigned> ViewHotFreqPercent;
 
 namespace llvm {