[IR] Change std::sort to llvm::sort in response to r327219

r327219 added wrappers to std::sort which randomly shuffle the container before
sorting.  This will help in uncovering non-determinism caused due to undefined
sorting order of objects having the same key.

To make use of that infrastructure we need to invoke llvm::sort instead of
std::sort.

Note: This patch is one of a series of patches to replace *all* std::sort to
llvm::sort.  Refer D44363 for a list of all the required patches.

llvm-svn: 329353
diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index 92bb53b..cd24915 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -2257,7 +2257,7 @@
   if (isa<PHINode>(BB.front())) {
     SmallVector<BasicBlock*, 8> Preds(pred_begin(&BB), pred_end(&BB));
     SmallVector<std::pair<BasicBlock*, Value*>, 8> Values;
-    std::sort(Preds.begin(), Preds.end());
+    llvm::sort(Preds.begin(), Preds.end());
     for (const PHINode &PN : BB.phis()) {
       // Ensure that PHI nodes have at least one entry!
       Assert(PN.getNumIncomingValues() != 0,
@@ -2275,7 +2275,7 @@
       for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
         Values.push_back(
             std::make_pair(PN.getIncomingBlock(i), PN.getIncomingValue(i)));
-      std::sort(Values.begin(), Values.end());
+      llvm::sort(Values.begin(), Values.end());
 
       for (unsigned i = 0, e = Values.size(); i != e; ++i) {
         // Check to make sure that if there is more than one entry for a