#include <endian.h> is missing?

I end up with errors like:

````
ar71xx/source/build_dir/target-mips_24kc_musl/linux-ath79_generic/ndpi-netfilter2-flow_info-c8ee735-2.8/ndpi-netfilter/src/../../src/include/ndpi_define.h:61:21: warning: "__LITTLE_ENDIAN" is not defined, evaluates to 0 [-Wundef]
 #if __BYTE_ORDER == __LITTLE_ENDIAN
                     ^~~~~~~~~~~~~~~

````