Remove unnecessary forward declarations from the docview sample.

MyFrame doesn't exist at all and was just confusing; DrawingView does exist
but is declared in view.h and is not needed in this header.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74932 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Turkish translations update from Kaya Zeren.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74933 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Work around g++ atomic builtins detection in configure when -Os is used.

Assigning __sync_sub_and_fetch() result to an unused variable can result in it
being optimized away and the function support is then not really tested for,
see #4542. So do make sure this variable is kept by making it volatile.

Closes #15555.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74934 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775