Move .debug_gdb_script processing to auto-load.c.

Move .debug_gdb_script processing to auto-load.c.
Simplify handling of auto-loaded objfile scripts.

.debug_gdb_scripts was always intended to handle more than just python,
thus the rightful home for the code that processes it is not in py-foo.c.
This is just a cleanup to move the code to a better place.

This also simplifies the handling of the ${objfile}-${suffix} auto-loaded
scripts.  There's no need for each of the the handlers to do is-safe-to-load
checking, or call maybe_add_script.  Doing it in the caller removes the
duplication.

	* auto-load.h (script_language): New members name, auto_load_enabled.
	Add missing comments on struct members.
	(auto_load_objfile_script): Delete.
	* auto-load.c: #include "cli/cli-cmds.h".
	(auto_load_gdb_scripts_enabled): New function.
	(script_language_gdb): Update, add new members.
	(source_gdb_script_for_objfile): Simplify, auto-load safe-checking
	and call to maybe_add_script moved to caller.
	(auto_load_objfile_script_1): Auto-load safe-checking and
	call to maybe_add_script moved here.
	(auto_load_objfile_script): Make static.  Early exit if support for
	scripting language hasn't been compiled in, or auto-loading has been
	disabled.
	(source_section_scripts): Argument "source_name" renamed to
	"section_name".  All uses updated.  Replace uses of AUTO_SECTION_NAME
	with section_name.  Skip loading script if support for scripting
	language hasn't been compiled in, or auto-loading has been disabled.
	Call language->source_script_for_objfile instead of calling
	source_python_script_for_objfile directly.
	(load_auto_scripts_for_objfile): Update.
	* python/py-auto-load.c: Delete #include "cli/cli-cmds.h".
	(gdbpy_load_auto_script_for_objfile): Delete.
	(auto_load_python_scripts_enabled): New function.
	(script_language_python): Update, add new members.
	(gdbpy_script_language_defn): New function.
	* python/python.h (gdbpy_load_auto_scripts_for_objfile): Delete.
	(gdbpy_script_language_defn): Declare.

	* auto-load.c (AUTO_SECTION_NAME): Moved here and renamed from
	py-auto-load.c, GDBPY_AUTO_SECTION_NAME.
	(source_section_scripts): Moved here from py-auto-load.c.
	(auto_load_section_scripts): Ditto.
	* python/py-auto-load.c (GDBPY_AUTO_SECTION_NAME): Moved to
	auto-load.c, renamed AUTO_SECTION_NAME.
	(source_section_scripts, auto_load_section_scripts): Moved to
	auto-load.c.