[X86] Remove Redundant memset Calls

These calls were added in 8d51149 to
keep valgrind quiet. They are redundant, and I'm not aware of anyone
attempting to run LLVM under valgrind these days, so deleting them.

Author: boomanaiden154

llvm/lib/Target/X86/X86FloatingPoint.cpp

@@ -58,12 +58,7 @@ namespace {
 
   struct FPS : public MachineFunctionPass {
     static char ID;
-    FPS() : MachineFunctionPass(ID) {
-      // This is really only to keep valgrind quiet.
-      // The logic in isLive() is too much for it.
-      memset(Stack, 0, sizeof(Stack));
-      memset(RegMap, 0, sizeof(RegMap));
-    }
+    FPS() : MachineFunctionPass(ID) {}
 
     void getAnalysisUsage(AnalysisUsage &AU) const override {
       AU.setPreservesCFG();