gcc -Iinclude/ -Isrc/ -Wall -Wno-unknown-pragmas -Wfatal-errors -fPIC -Ofast -c ./src/utils.c -o obj/utils.o
./src/utils.c:29:5: warning: implicit declaration of function 'clock_gettime' is invalid in C99 [-Wimplicit-function-declaration]
clock_gettime(CLOCK_REALTIME, &now);
^
./src/utils.c:29:19: fatal error: use of undeclared identifier 'CLOCK_REALTIME'
clock_gettime(CLOCK_REALTIME, &now);
^
生成 1 个警告和 1 个错误。make: *** [obj/utils.o] 错误 1