Revert "fix header file"

This reverts commit 4eb81994.

sys/unistd.h is not a standard header file, not found on musl system.
It is supposed to be unneeded.

src/66/66-inservice.c

@@ -16,7 +16,6 @@
 #include <locale.h>
 #include <langinfo.h>
 #include <sys/types.h>
-#include <sys/unistd.h>
 #include <wchar.h>
 #include <unistd.h>
 //#include <stdio.h>