More build fixes. Changed the documentation builder to automatically prepend %EPOCROOT% (converted to a path relative form) to pre-processor include path options that start with 'epoc32'. Prevously $(EPOCROOT) was prepended in the makefile, which broke the documentation build because the pre-processor will only accecpt relative path include options.

(binary:application/vnd.openxmlformats-officedocument.presentationml.presentation)