Remove initialize_utils
    
    initialize_utils only registers some commands, so it isn't necessary
    to run it at any particular time during startup.  This patch removes
    it and merges its contents into _initialize_utils.
    
    Tested by the buildbot.
    
    gdb/ChangeLog
    2019-09-26  Tom Tromey  <tom@tromey.com>
    
    	* utils.h (initialize_utils): Don't declare.
    	* top.c (gdb_init): Don't call initialize_utils.
    	* utils.c (initialize_utils): Remove.  Move contents...
    	(_initialize_utils): ... here.