Change all self assignments X=X to (void)X, so that we can turn on a
new gcc warning that complains on self-assignments and
self-initializations.

llvm-svn: 122458
diff --git a/llvm/lib/VMCore/Value.cpp b/llvm/lib/VMCore/Value.cpp
index 76cfb90..36e6b4c 100644
--- a/llvm/lib/VMCore/Value.cpp
+++ b/llvm/lib/VMCore/Value.cpp
@@ -255,7 +255,7 @@
   // Get V's ST, this should always succed, because V has a name.
   ValueSymbolTable *VST;
   bool Failure = getSymTab(V, VST);
-  assert(!Failure && "V has a name, so it should have a ST!"); Failure=Failure;
+  assert(!Failure && "V has a name, so it should have a ST!"); (void)Failure;
 
   // If these values are both in the same symtab, we can do this very fast.
   // This works even if both values have no symtab yet.