Add support for auto-loading scripts from .debug_gdb_scripts section.

	Add support for auto-loading scripts from .debug_gdb_scripts section.
	* NEWS: Add entry for .debug_gdb_scripts.
	* Makefile.in SUBDIR_PYTHON_OBS): Add py-auto-load.o.
	(SUBDIR_PYTHON_SRCS): Add py-auto-load.c.
	(py-auto-load.o): New rule.
	* cli/cli-cmds.c (find_and_open_script): Make externally visible.
	* cli/cli-cmds.h (find_and_open_script): Update prototype.
	* python/py-auto-load.c: New file.
	* python/python-internal.h: #include <stdio.h>.
	(set_python_list, show_python_list): Declare.
	(gdbpy_initialize_auto_load): Declare.
	(source_python_script_for_objfile): Declare.
	* python/python.c: Remove #include of observer.h.
	(gdbpy_auto_load): Moved to py-auto-load.c.
	(GDBPY_AUTO_FILENAME): Ditto.
	(gdbpy_new_objfile): Delete.
	(source_python_script_for_objfile): New function.
	(set_python_list, show_python_list): Make externally visible.
	(_initialize_python): Move "auto-load" command to py-auto-load.c
	and observer_attach_new_objfile to py-auto-load.c.

	doc/
	* gdb.texinfo (Python): Move Auto-loading section here ...
	(Python API): from here.
	(Auto-loading): Add docs for .debug_gdb_scripts auto-loaded scripts.
	(Maintenance Commands): Add docs for "maint print section-scripts".

	testsuite/
	* gdb.python/py-section-script.c: New file.
	* gdb.python/py-section-script.exp: New file.
	* gdb.python/py-section-script.py: New file.