Add assignment of "buffer size" parameter when buffer is succesfully assigned (in buffer-oriented methods)

[Vlad]

For example in
DGLE_RESULT DGLE_API CHDDFileIterator::FileName(char *pcName, uint &uiCharsCount)
succesfull part of method is
if (strlen(_acName) < uiCharsCount) { strcpy(pcName, _acName); return S_OK; }
adding
uiCharsCount = strlen(_acName) + 1;
makes it more convenient to interoperate