[clang] 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.

llvm-svn: 328636
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 84ab923..d8bd500 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1278,7 +1278,7 @@
     Success = false;
   }
   else
-    std::sort(Opts.VerifyPrefixes.begin(), Opts.VerifyPrefixes.end());
+    llvm::sort(Opts.VerifyPrefixes.begin(), Opts.VerifyPrefixes.end());
   DiagnosticLevelMask DiagMask = DiagnosticLevelMask::None;
   Success &= parseDiagnosticLevelMask("-verify-ignore-unexpected=",
     Args.getAllArgValues(OPT_verify_ignore_unexpected_EQ),
@@ -2409,7 +2409,7 @@
   Opts.CurrentModule = Opts.ModuleName;
   Opts.AppExt = Args.hasArg(OPT_fapplication_extension);
   Opts.ModuleFeatures = Args.getAllArgValues(OPT_fmodule_feature);
-  std::sort(Opts.ModuleFeatures.begin(), Opts.ModuleFeatures.end());
+  llvm::sort(Opts.ModuleFeatures.begin(), Opts.ModuleFeatures.end());
   Opts.NativeHalfType |= Args.hasArg(OPT_fnative_half_type);
   Opts.NativeHalfArgsAndReturns |= Args.hasArg(OPT_fnative_half_arguments_and_returns);
   // Enable HalfArgsAndReturns if present in Args or if NativeHalfArgsAndReturns