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

Summary:
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 the comments section in D44363 for a list of all the required patches.

Reviewers: bogner, rnk, MatzeB, RKSimon

Reviewed By: rnk

Subscribers: JDevlieghere, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D45133

llvm-svn: 329435
diff --git a/llvm/lib/CodeGen/SlotIndexes.cpp b/llvm/lib/CodeGen/SlotIndexes.cpp
index ea74c77..0b8a0f9 100644
--- a/llvm/lib/CodeGen/SlotIndexes.cpp
+++ b/llvm/lib/CodeGen/SlotIndexes.cpp
@@ -94,7 +94,7 @@
   }
 
   // Sort the Idx2MBBMap
-  std::sort(idx2MBBMap.begin(), idx2MBBMap.end(), Idx2MBBCompare());
+  llvm::sort(idx2MBBMap.begin(), idx2MBBMap.end(), Idx2MBBCompare());
 
   DEBUG(mf->print(dbgs(), this));