MDEV-31505 Deprecate mariabackup --innobackupex mode

1. "mariabackup --innobackupex" now prints a new warning:
       '--innobackupex' is deprecated and will be removed in a future release

2. "mariabackup --innobackupex" does not print this wrong warning any more:
        --innobackupex: Deprecated program name.
          It will be removed in a future release,
          use '/path/to/mariadb-backup' instead

extra/mariabackup/xtrabackup.cc

@@ -6778,6 +6778,12 @@ int main(int argc, char **argv)
 		}
 		if(strcmp(argv[1], "--innobackupex") == 0)
 		{
+			/*
+			  my_init() prints a "Deprecated program name"
+			  warning if argv[0] does not start with "mariadb".
+			  So pass the original argv[0] as the new argv[0].
+			*/
+			argv[1]= argv[0];
 			argv++;
 			argc--;
 			innobackupex_mode = true;
@@ -6853,6 +6859,8 @@ int main(int argc, char **argv)
 static int main_low(char** argv)
 {
 	if (innobackupex_mode) {
+		msg(ER_DEFAULT(ER_WARN_DEPRECATED_SYNTAX_NO_REPLACEMENT),
+			"--innobackupex");
 		if (!ibx_init()) {
 			return(EXIT_FAILURE);
 		}

mysql-test/suite/mariabackup/innodb_force_recovery.result

@@ -8,6 +8,14 @@ FOUND 1 /should only be used with "--apply-log"/ in backup.log
 FOUND 1 /innodb_force_recovery = 1/ in backup.log
 # "innodb_force_recovery" should be limited to "SRV_FORCE_IGNORE_CORRUPT" (innobackupex)
 FOUND 1 /innodb_force_recovery = 1/ in backup.log
+#
+# This fragment was added for MDEV-31505 Deprecate mariabackup --innobackupex mode
+#
+NOT FOUND /Deprecated program name/ in backup.log
+FOUND 1 /[-][-]innobackupex.*is deprecated and will be removed in a future release/ in backup.log
+#
+# End of the MDEV-31505 fragment
+#
 # "innodb_force_recovery" should be read from "backup-my.cnf" (mariabackup)
 FOUND 1 /innodb_force_recovery = 1/ in backup.log
 # "innodb_force_recovery=1" should be read from "backup-my.cnf" (innobackupex)

mysql-test/suite/mariabackup/innodb_force_recovery.test

@@ -52,6 +52,16 @@ exec $XTRABACKUP --innobackupex --apply-log --innodb-force-recovery=2 $targetdir
 --let SEARCH_PATTERN=innodb_force_recovery = 1
 --let SEARCH_FILE=$backuplog
 --source include/search_pattern_in_file.inc
+--echo #
+--echo # This fragment was added for MDEV-31505 Deprecate mariabackup --innobackupex mode
+--echo #
+--let SEARCH_PATTERN=Deprecated program name
+--source include/search_pattern_in_file.inc
+--let SEARCH_PATTERN=[-][-]innobackupex.*is deprecated and will be removed in a future release
+--source include/search_pattern_in_file.inc
+--echo #
+--echo # End of the MDEV-31505 fragment
+--echo #
 rmdir $targetdir;
 
 # Check for default file ("backup-my.cnf").