Test PR python/11407.
* gdb.dwarf2/dw2-ref-missing-frame-func.c: New file.
* gdb.dwarf2/dw2-ref-missing-frame.S: Use cu_text_start and cu_text_end.
Split main into func_nofb and func_loopfb dropping NO_FRAME_BASE.
* gdb.dwarf2/dw2-ref-missing-frame.exp: Remove variables sources,
executable_nofb and executable_fb. New variables srcsfile, objsfile,
srcfuncfile, objfuncfile, srcmainfile, objmainfile, executable and
binfile. Call gdb_compile with clean_restart twice.
(func_nofb print, func_nofb backtrace, func_loopfb print)
(func_loopfb backtrace): New.
