[OpenMPOpt] Use SetVector to store list of kernels.

Fixes test failures on reverse-iteration buildbot.

llvm/include/llvm/Transforms/IPO/OpenMPOpt.h

@@ -21,7 +21,7 @@ namespace omp {
 using Kernel = Function *;
 
 /// Set of kernels in the module
-using KernelSet = SmallPtrSet<Kernel, 4>;
+using KernelSet = SetVector<Kernel>;
 
 /// Helper to determine if \p M contains OpenMP.
 bool containsOpenMP(Module &M);

llvm/lib/Transforms/IPO/OpenMPOpt.cpp

@@ -163,7 +163,7 @@ struct AAICVTracker;
 struct OMPInformationCache : public InformationCache {
   OMPInformationCache(Module &M, AnalysisGetter &AG,
                       BumpPtrAllocator &Allocator, SetVector<Function *> &CGSCC,
-                      SmallPtrSetImpl<Kernel> &Kernels)
+                      KernelSet &Kernels)
       : InformationCache(M, AG, Allocator, &CGSCC), OMPBuilder(M),
         Kernels(Kernels) {
 
@@ -478,7 +478,7 @@ struct OMPInformationCache : public InformationCache {
   }
 
   /// Collection of known kernels (\see Kernel) in the module.
-  SmallPtrSetImpl<Kernel> &Kernels;
+  KernelSet &Kernels;
 
   /// Collection of known OpenMP runtime functions..
   DenseSet<const Function *> RTLFunctions;