* prevent going through (the expensive) InternalSetCodePage when changing
    the code page of a string with refcount=1 and without conversion (happens
    a lot in internal RTL routines)


git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@24985 3ad0048d-3df7-0310-abae-a5850022a9f2