load_param and load_model functions are causing memory leaks

[radhigithub55]

I am loading models using these two methods of ncnn and using it in my swift project, its causing lot of memory leaks.

// load network structure from external memory
// memory pointer must be 32-bit aligned
// return bytes consumed
int load_param(const unsigned char* mem);

// reference network weight data from external memory
// weight data is not copied but referenced
// so external memory should be retained when used
// memory pointer must be 32-bit aligned
// return bytes consumed
int load_model(const unsigned char* mem);