[fusl] Don't syscall(SYS_unlink) in stdio

fusl/src/stdio/tmpfile.c

 #include <stdio.h>
 #include <fcntl.h>
+#include <unistd.h>
 #include "stdio_impl.h"
 
 #define MAXTRIES 100
 
 char* __randname(char*);
 
 FILE* tmpfile(void) {
   char s[] = "/tmp/tmpfile_XXXXXX";
   int fd;
   FILE* f;
   int try
     ;
   for (try = 0; try < MAXTRIES; try ++) {
     __randname(s + 13);
     fd = sys_open(s, O_RDWR | O_CREAT | O_EXCL, 0600);
     if (fd >= 0) {
-#ifdef SYS_unlink
-      __syscall(SYS_unlink, s);
-#else
-      __syscall(SYS_unlinkat, AT_FDCWD, s, 0);
-#endif
+      unlink(s);
       f = __fdopen(fd, "w+");
       if (!f)
         __syscall(SYS_close, fd);
       return f;
     }
   }
   return 0;
 }