Refactoring: removing reference to long removed type BufStr

Author: doxygen

src/doxygen.h

@@ -34,7 +34,6 @@ class RefList;
 class PageLinkedMap;
 class PageDef;
 class ParserManager;
-class BufStr;
 class MemberDef;
 class GroupDef;
 class GroupLinkedMap;

src/util.h

@@ -53,7 +53,6 @@ struct TagInfo;
 class PageDef;
 class SectionInfo;
 class Definition;
-class BufStr;
 class FileInfo;
 class Dir;