MDEV-8378 - Debian: the Lintian complains about many "shlib-calls-exit" in many

            of the plugins

Removed exit() from daemon_example, pass error to caller instead.
Also removed unused my_abort_hook.

include/my_sys.h

@@ -259,8 +259,7 @@ extern myf      my_global_flags;        /* Set to MY_WME for more error messages
 					/* Point to current my_message() */
 extern void (*my_sigtstp_cleanup)(void),
 					/* Executed before jump to shell */
-	    (*my_sigtstp_restart)(void),
-	    (*my_abort_hook)(int);
+	    (*my_sigtstp_restart)(void);
 					/* Executed when comming from shell */
 extern MYSQL_PLUGIN_IMPORT int my_umask;		/* Default creation mask  */
 extern int my_umask_dir,

mysys/my_static.c

@@ -72,7 +72,6 @@ ulong my_time_to_wait_for_lock=2;	/* In seconds */
 #ifdef SHARED_LIBRARY
 const char *globerrs[GLOBERRS];		/* my_error_messages is here */
 #endif
-void (*my_abort_hook)(int) = (void(*)(int)) exit;
 void (*error_handler_hook)(uint error, const char *str, myf MyFlags)=
   my_message_stderr;
 void (*fatal_error_handler_hook)(uint error, const char *str, myf MyFlags)=

plugin/daemon_example/daemon_example.cc

@@ -129,7 +129,7 @@ static int daemon_example_plugin_init(void *p __attribute__ ((unused)))
                      (void *)con) != 0)
   {
     fprintf(stderr,"Could not create heartbeat thread!\n");
-    exit(0);
+    DBUG_RETURN(1);
   }
   plugin->data= (void *)con;
 

sql/init.cc

@@ -42,9 +42,6 @@ void unireg_init(ulong options)
 
   current_pid=(ulong) getpid();		/* Save for later ref */
   my_init_time();			/* Init time-functions (read zone) */
-#ifndef EMBEDDED_LIBRARY
-  my_abort_hook=unireg_abort;		/* Abort with close of databases */
-#endif
 
   (void) strmov(reg_ext,".frm");
   reg_ext_length= 4;