rtl: apply patch of Inoussa which fixes undefined result of UnicodeToLower and UnicodeToUpper (mantis #0024889)

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25315 3ad0048d-3df7-0310-abae-a5850022a9f2
tests: fix test to use fpwidestring manager (by Inoussa, mantis #0024890)

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25316 3ad0048d-3df7-0310-abae-a5850022a9f2