[ASTImporter] Import "implicit" attribute of FunctionDecls

[labath]

Summary

ASTImporter was importing this attribute only on destructor and constructor decls, as they take
it in the constructor, but other decls can have this attribute as well, notably the global
operator new. Make sure we import the attribute on all FunctionDecls.

[labath]

I noticed this while debugging an importing issue in LLDB.

I am not sure if I have selected the right reviewer, and also how/if to test this...

lib/AST/ASTImporter.cpp

Decl *ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
 
   // Import the qualifier, if any.
   ToFunction->setQualifierInfo(Importer.Import(D->getQualifierLoc()));
   ToFunction->setAccess(D->getAccess());
   ToFunction->setLexicalDeclContext(LexicalDC);
   ToFunction->setVirtualAsWritten(D->isVirtualAsWritten());
   ToFunction->setTrivial(D->isTrivial());
   ToFunction->setPure(D->isPure());
+  ToFunction->setImplicit(D->isImplicit());
   Importer.Imported(D, ToFunction);
 
   // Set the parameters.
   for (unsigned I = 0, N = Parameters.size(); I != N; ++I) {
     Parameters[I]->setOwningFunction(ToFunction);
     ToFunction->addDeclInternal(Parameters[I]);
   }
   ToFunction->setParams(Parameters);