Use const_cast to make it obvious that it's just removing constness (and silence warnings).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@143193 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/libclang/CIndexUSRs.cpp b/tools/libclang/CIndexUSRs.cpp
index 1219c2e..11b124c 100644
--- a/tools/libclang/CIndexUSRs.cpp
+++ b/tools/libclang/CIndexUSRs.cpp
@@ -817,7 +817,7 @@
 
   {
     USRGenerator UG(&D->getASTContext(), &Buf);
-    UG->Visit((Decl*)D);
+    UG->Visit(const_cast<Decl*>(D));
 
     if (UG->ignoreResults())
       return true;