clang -O2  -Wall -Wextra -Werror=implicit-function-declaration endian/htobe16.c -o endian/htobe16 -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm  -lintl
endian/htobe16.c:3:10: fatal error: 'endian.h' file not found
#include <endian.h>
         ^
1 error generated.