Remove unused JIMAGE_ResourcePath

GCC 8.2 generates warnings for a the uses of strncpy in ImageFileReader::location_path (libjimage/imageFile.cpp):

libjimage/imageFile.cpp:502:16: error: 'char* strncpy(char*, const char*, size_t)' output truncated before terminating nul copying as many bytes from a string as its length [-Werror=stringop-truncation]
         strncpy(next, module, length); next += length;
         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

The code in question is only used by JIMAGE_ResourcePath, and that function is in itself unused so should be removed.