Remove Palm OS port.

The platform targeted by this port doesn't exist any more and the port never
achieved really working state so remove the code to avoid having to maintain
it.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70345 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/file.cpp

@@ -80,8 +80,6 @@
     char* mktemp( char * path ) { return path ;}
     #include <stat.h>
     #include <unistd.h>
-#elif defined(__WXPALMOS__)
-    #include "wx/palmos/missing.h"
 #else
     #error  "Please specify the header with file functions declarations."
 #endif  //Win/UNIX