2009-06-29  Olatunji Ruwase   <tjruwase@google.com>

	* doc/plugins.texi: Document PLUGIN_START_UNIT.
	* toplev.c (compile_file): Call PLUGIN_START_UNIT.
	* gcc-plugin.h (PLUGIN_START_UNIT): Added new event.
	* plugin.c (plugin_event_name): Added PLUGIN_START_UNIT.
	(register_callback): Handle PLUGIN_START_UNIT.
	(invoke_plugin_callbacks): Handle PLUGIN_START_UNIT.

From-SVN: r149064