Add include to use PMA mb_* functions.

Signed-off-by: Hugues Peccatte <hugues.peccatte@gmail.com>
Merge branch 'stringFunctions_master' of https://github.com/Tithugues/phpmyadmin into stringFunctions_master
Replace PMA_String calls by mb_* calls in tests.

Signed-off-by: Hugues Peccatte <hugues.peccatte@gmail.com>
Revert use of multibytes functions to get compression mime type.

Signed-off-by: Hugues Peccatte <hugues.peccatte@gmail.com>