Include sys/syscall.h since we are checking for __NR_clock_getres.

libc/unistd/sysconf.c

@@ -27,6 +27,7 @@
 #include <stdlib.h>
 #include <time.h>
 #include <unistd.h>
+#include <sys/syscall.h>
 #include <sys/sysinfo.h>
 #include <sys/types.h>
 #ifdef __UCLIBC_HAS_REGEX__