Memory leak when reading compressed headers in PNGs

[luis-vsn]

Hello mantainers,

I have found a memory leak when referencing the library from another project. It leaks memory when PNG files have compressed headres so they need to be uncompressed using zlib.

PoC cursed.zip

To reproduce it, just add a loop after main analysis in HowToUse_Dll.cpp:

MI.Close();
int i = 0;
do {
    MI.Open(__T("cursed.png"));
    MI.Close();
} while (i++ < 1000);

This leak does not apply when analyzing the file with CLI.

[JeromeMartinez]

https://github.com/MediaArea/MediaInfoLib/pull/2121