Use wxGetTranslation() instead of _() in the public headers.

This allows the code in them to compile even when WXINTL_NO_GETTEXT_MACRO is
defined.

Closes #15443.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74812 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/unix/pipe.h

@@ -44,7 +44,7 @@ public:
     {
         if ( pipe(m_fds) == -1 )
         {
-            wxLogSysError(_("Pipe creation failed"));
+            wxLogSysError(wxGetTranslation("Pipe creation failed"));
 
             return false;
         }