Remove checks for ancient gcc/MinGW versions.

Don't test for wxUSE_NORLANDER_HEADERS, this is always true since many, many
years.

Remove tests for gcc version < 3.3, notably 2.95: the minimal supported gcc
version is 3.4.

Closes #15727.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76549 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/doxygen/mainpages/const_wxusedef.h

@@ -330,7 +330,6 @@ library:
 @itemdef{wxUSE_MS_HTML_HELP, Use wxCHMHelpController class.}
 @itemdef{wxUSE_NO_MANIFEST, Can be predefined to disable inclusion of the
 manifest from wxWidgets RC file. See also wxUSE_RC_MANIFEST.}
-@itemdef{wxUSE_NORLANDER_HEADERS, Using headers whose author is Anders Norlander.}
 @itemdef{wxUSE_OLE, Enables OLE helper routines.}
 @itemdef{wxUSE_OLE_AUTOMATION, Enable OLE automation utilities.}
 @itemdef{wxUSE_OLE_CLIPBOARD, Use OLE clipboard.}