define HeUTF8 macro for perl 5.10 and perls < 5.8.9
define HeUTF8 macro for perl 5.10 and perls < 5.8.9

The HeUTF8 macro was added to 5.10.1 and backported to 5.8.9.  It is
not yet provided by ppport.h so this adds it to our own header

gormanb/mongo-perl-driver,gormanb/mongo-perl-driver,jorol/mongo-perl-driver,gormanb/mongo-perl-driver,jorol/mongo-perl-driver,jorol/mongo-perl-driver,xdg/mongo-perl-driver,dagolden/mongo-perl-driver,dagolden/mongo-perl-driver,dagolden/mongo-perl-driver,kainwinterheart/mongo-perl-driver,dagolden/mongo-perl-driver,rahuldhodapkar/mongo-perl-driver,rahuldhodapkar/mongo-perl-driver,mongodb/mongo-perl-driver,rahuldhodapkar/mongo-perl-driver,mongodb/mongo-perl-driver,rahuldhodapkar/mongo-perl-driver,kainwinterheart/mongo-perl-driver,jorol/mongo-perl-driver,kainwinterheart/mongo-perl-driver,mongodb/mongo-perl-driver,kainwinterheart/mongo-perl-driver,xdg/mongo-perl-driver,xdg/mongo-perl-driver,gormanb/mongo-perl-driver