cppcheck: some cleanings

Fix all Prefer prefix ++/-- operators for non-primitive type

[src/data.cpp:107]: (error) Width 4 given in format string (no. 2) is larger than destination buffer 'symbol[4]', use %3s to prevent overflowing it.
[src/formats/libinchi/ichimake.c:2088] -> [src/formats/libinchi/ichimake.c:2088]: (style) Same expression on both sides of '||'.
I don't know if this is the correct fix. I tend to hold off on changing things in the InChI code, rather referring them to the InChI developers.