[OPENMP50]Add 'default' modifier in reduction clauses.

Added full support for 'default' modifier in the reduction clauses.
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index f308246..ec75ff5 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -6242,7 +6242,9 @@
   Record.push_back(C->varlist_size());
   VisitOMPClauseWithPostUpdate(C);
   Record.AddSourceLocation(C->getLParenLoc());
+  Record.AddSourceLocation(C->getModifierLoc());
   Record.AddSourceLocation(C->getColonLoc());
+  Record.writeEnum(C->getModifier());
   Record.AddNestedNameSpecifierLoc(C->getQualifierLoc());
   Record.AddDeclarationNameInfo(C->getNameInfo());
   for (auto *VE : C->varlists())