simplify-libcalls: Removed unused variable

The 'Modified' variable should have been removed from SimplifyLibCalls
in r177619, but was missed.  This commit removes it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177622 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/SimplifyLibCalls.cpp

@@ -89,8 +89,6 @@ namespace {
     TargetLibraryInfo *TLI;
 
     StringMap<LibCallOptimization*> Optimizations;
-
-    bool Modified;  // This is only used by doInitialization.
   public:
     static char ID; // Pass identification
     SimplifyLibCalls() : FunctionPass(ID) {