[X86] Fix sanitizer bot failure from 344085

Fix the memory issue exposed by sanitizer.

llvm-svn: 344092
diff --git a/llvm/lib/Target/X86/X86CondBrFolding.cpp b/llvm/lib/Target/X86/X86CondBrFolding.cpp
index 9a5ae70..8b9ef20 100644
--- a/llvm/lib/Target/X86/X86CondBrFolding.cpp
+++ b/llvm/lib/Target/X86/X86CondBrFolding.cpp
@@ -424,8 +424,9 @@
   }
   NumFixedCondBrs += RemoveList.size();
   for (auto MBBI : RemoveList) {
-    for (auto *Succ : MBBI->successors())
-      MBBI->removeSuccessor(Succ);
+    while (!MBBI->succ_empty())
+      MBBI->removeSuccessor(MBBI->succ_end() - 1);
+
     MBBI->eraseFromParent();
   }