MDEV-5054 Failing test(s): main.mysqld--help sys_vars.character_sets_dir_basic

fix tests where a path was used as a regex.
revert changes to sys_vars.character_sets_dir_basic - we don't run it on windows anyway

mysql-test/suite/sys_vars/r/character_sets_dir_basic.result

 select @@global.character_sets_dir;
 @@global.character_sets_dir
-MYSQL_CHARSETSDIR
+MYSQL_CHARSETSDIR/
 select @@session.character_sets_dir;
 ERROR HY000: Variable 'character_sets_dir' is a GLOBAL variable
 show global variables like 'character_sets_dir';
 Variable_name	Value
-character_sets_dir	MYSQL_CHARSETSDIR
+character_sets_dir	MYSQL_CHARSETSDIR/
 show session variables like 'character_sets_dir';
 Variable_name	Value
-character_sets_dir	MYSQL_CHARSETSDIR
+character_sets_dir	MYSQL_CHARSETSDIR/
 select * from information_schema.global_variables where variable_name='character_sets_dir';
 VARIABLE_NAME	VARIABLE_VALUE
-CHARACTER_SETS_DIR	MYSQL_CHARSETSDIR
+CHARACTER_SETS_DIR	MYSQL_CHARSETSDIR/
 select * from information_schema.session_variables where variable_name='character_sets_dir';
 VARIABLE_NAME	VARIABLE_VALUE
-CHARACTER_SETS_DIR	MYSQL_CHARSETSDIR
+CHARACTER_SETS_DIR	MYSQL_CHARSETSDIR/
 set global character_sets_dir="foo";
 ERROR HY000: Variable 'character_sets_dir' is a read only variable
 set session character_sets_dir="foo";

mysql-test/suite/sys_vars/t/character_sets_dir_basic.test

@@ -2,26 +2,17 @@
 #
 # show the global and session values;
 #
-
-# workaround to adjust for the directory separators being different in 
-# different OSes : slash on unixes and backslash or slash on windows.
-# TODO: fix with a proper comparison in mysqltest
-let $rcd= `SELECT REPLACE('$MYSQL_CHARSETSDIR', '\\\\\', '.')`;
-let $rcd= `SELECT REPLACE('$rcd', '/', '.')`;
-let $regex_charsetdir= `SELECT '/$rcd[\\\\\/\\\\\]/MYSQL_CHARSETSDIR/'`;
-
---replace_regex $regex_charsetdir
+--replace_result $MYSQL_CHARSETSDIR MYSQL_CHARSETSDIR
 select @@global.character_sets_dir;
-
 --error ER_INCORRECT_GLOBAL_LOCAL_VAR
 select @@session.character_sets_dir;
---replace_regex $regex_charsetdir
+--replace_result $MYSQL_CHARSETSDIR MYSQL_CHARSETSDIR
 show global variables like 'character_sets_dir';
---replace_regex $regex_charsetdir
+--replace_result $MYSQL_CHARSETSDIR MYSQL_CHARSETSDIR
 show session variables like 'character_sets_dir';
---replace_regex $regex_charsetdir
+--replace_result $MYSQL_CHARSETSDIR MYSQL_CHARSETSDIR
 select * from information_schema.global_variables where variable_name='character_sets_dir';
---replace_regex $regex_charsetdir
+--replace_result $MYSQL_CHARSETSDIR MYSQL_CHARSETSDIR
 select * from information_schema.session_variables where variable_name='character_sets_dir';
 
 #

mysql-test/t/mysqld--help.test

@@ -53,7 +53,7 @@ perl;
     s/\b2146435072\b/9223372036853727232/;
     s/\b196608\b/262144/;
     s/\b4294963200\b/18446744073709547520/;
-    foreach $var (@env) { s/$ENV{$var}/$var/ }
+    foreach $var (@env) { s/\Q$ENV{$var}\E/$var/ }
     next if /use --skip-(use-)?symbolic-links to disable/; # for valgrind, again
     next if $skip;
     print;