NKR_CPP_USE_APPDATA not able to be set through cmake flags

[TomaSajt]

Description suggestions

The ability to get cmake to define NKR_CPP_USE_APPDATA was removed in 3f738ce. Previously I was setting NKR_PACKAGE to achieve this. (I only used NKR_PACKAGE for this behaviour). Now I have to patch the code or force the compiler to define it using hacky methods.

Consider adding back the ability to set NKR_CPP_USE_APPDATA, in some way.

Necessity of recommendations

This is not very important, since I'm able to patch it anyways, just wanted to share this, in case this removal was an accident.