[Hexagon] 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: kparzysz

Reviewed By: kparzysz

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D44857

llvm-svn: 328430
diff --git a/llvm/lib/Target/Hexagon/RDFGraph.cpp b/llvm/lib/Target/Hexagon/RDFGraph.cpp
index d1f6e5a..ceb4887 100644
--- a/llvm/lib/Target/Hexagon/RDFGraph.cpp
+++ b/llvm/lib/Target/Hexagon/RDFGraph.cpp
@@ -1471,7 +1471,7 @@
   // and add a def for each S in the closure.
 
   // Sort the refs so that the phis will be created in a deterministic order.
-  std::sort(MaxRefs.begin(), MaxRefs.end());
+  llvm::sort(MaxRefs.begin(), MaxRefs.end());
   // Remove duplicates.
   auto NewEnd = std::unique(MaxRefs.begin(), MaxRefs.end());
   MaxRefs.erase(NewEnd, MaxRefs.end());