Fix build problem by lower SmallSet<N> to a reasonable value

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@259424 91177308-0d34-0410-b5e6-96231b3b80d8

modularize/PreprocessorTracker.cpp

@@ -1276,7 +1276,7 @@ private:
   std::vector<HeaderHandle> HeaderStack;
   std::vector<HeaderInclusionPath> InclusionPaths;
   InclusionPathHandle CurrentInclusionPathHandle;
-  llvm::SmallSet<HeaderHandle, 128> HeadersInThisCompile;
+  llvm::SmallSet<HeaderHandle, 32> HeadersInThisCompile;
   std::vector<PPItemKey> IncludeDirectives;
   MacroExpansionMap MacroExpansions;
   ConditionalExpansionMap ConditionalExpansions;