[oe] htmldoc: remove -native recipes

[Vitus Jensen]

The following patches switch htmldoc to BBCLASSEXTEND = "native".

1.8.27 is the same revision as ever.  For 1.9.x I wanted to update to the latest
snapshot revision at the same time but failed because gcc 4.4.3 reported far
too many errors in the -native compile.  So the recipe of 1.9.x is ready for
updates (just select SVN revision) but it's still the same old rev 1571.