print more digits for floating point options in in mariadbd --help

mysql-test/main/mysqld--help.result

@@ -1748,7 +1748,7 @@ log-queries-not-using-indexes FALSE
 log-short-format FALSE
 log-slave-updates FALSE
 log-slow-admin-statements TRUE
-log-slow-always-query-time 3.1536e+07
+log-slow-always-query-time 31536000
 log-slow-disabled-statements sp
 log-slow-filter admin,filesort,filesort_on_disk,filesort_priority_queue,full_join,full_scan,query_cache,query_cache_miss,tmp_table,tmp_table_on_disk
 log-slow-max-warnings 10
@@ -1960,7 +1960,7 @@ skip-name-resolve FALSE
 skip-networking FALSE
 skip-show-database FALSE
 skip-slave-start FALSE
-slave-abort-blocking-timeout 3.1536e+07
+slave-abort-blocking-timeout 31536000
 slave-compressed-protocol FALSE
 slave-connections-needed-for-purge 1
 slave-ddl-exec-mode IDEMPOTENT

mysys/my_getopt.c

@@ -1818,7 +1818,7 @@ void my_print_variables(const struct my_option *options)
 	printf("%s\n", buff);
 	break;
       case GET_DOUBLE:
-	printf("%g\n", *(double*) value);
+	printf("%.10g\n", *(double*) value);
 	break;
       case GET_NO_ARG:
 	printf("(No default value)\n");