gdb/testsuite/

gdb/testsuite/
	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.