added missing header file include

I thought it write() was in fcnttl

whoops

src/logger/lib/logger.c

@@ -4,6 +4,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <fcntl.h>
+#include <unistd.h>
 #include <dirent.h>
 #include <time.h>
 #include <sys/stat.h>