New remove-symbol-file command.

New remove-symbol-file command.

New command for removing symbol files added via
the add-symbol-file command.

2013-10-29  Nicolas Blanc  <nicolas.blanc@intel.com>

	* breakpoint.c (disable_breakpoints_in_freed_objfile): New function.
	* objfiles.c (free_objfile): Notify free_objfile.
	(is_addr_in_objfile): New function.
	* objfiles.h (is_addr_in_objfile): New declaration.
	* printcmd.c (clear_dangling_display_expressions): Act upon free_objfile
	events instead of solib_unloaded events.
	(_initialize_printcmd): Register observer for free_objfile instead
	of solib_unloaded notifications.
	* solib.c (remove_user_added_objfile): New function.
	* symfile.c (remove_symbol_file_command): New command.
	(_initialize_symfile): Add remove-symbol-file.
gdb/doc
	* observer.texi: New free_objfile event.

Signed-off-by: Nicolas Blanc <nicolas.blanc@intel.com>