* plugins/symbol-db/plugin.c
	(on_editor_buffer_symbols_update_timeout),
	(do_check_languages_count), (on_project_root_added),
	(on_scan_end_manager):
	* plugins/symbol-db/symbol-db-engine-core.c (sdb_engine_init),
	(symbol_db_engine_remove_file):
	* plugins/symbol-db/symbol-db-engine-priv.h:
	* plugins/symbol-db/symbol-db-engine-queries.c
	(symbol_db_engine_get_languages_count),
	(symbol_db_engine_is_language_used):
	* plugins/symbol-db/symbol-db-engine-queries.h:
	fixed #548910. 
	Hide the Global tab in case only C-files are used in a project.
	Enable it instead with 2+ different languages.

svn path=/trunk/; revision=4575