Code style in cache_flush() function

[mir-math]

First of all thanks for the library.
One minor correction:
function
static int cache_flush(TCHAR *buffer, int *size, INI_FILETYPE *rfp, INI_FILETYPE *wfp, INI_FILEPOS *mark);
uses constant INI_BUFFERSIZE as a size of its argument buffer. This is the case while library is unmodified but it would be safer to pass size of a buffer as an argument.