std::sys: use integrated Jule as much as possible instead of C++ linking

std/sys/syscall_unix.jule

@@ -2,25 +2,19 @@
 // Use of this source code is governed by a BSD 3-Clause
 // license that can be found in the LICENSE file.
 
-use std::jule::integrated::{Char}
+use integ for std::jule::integrated::{Char}
 
 cpp use "<dirent.h>"
 cpp use "<fcntl.h>"
 cpp use "<unistd.h>"
 
-cpp use "syscall_unix.hpp"
-
 #typedef
 cpp struct DIR{}
 
 cpp struct dirent {
     pub d_name: *Char
 }
 
-// This function actually equals to stat,
-// just interface to ignore identifier already exist error of compiler.
-cpp unsafe fn __jule_stat(path: *Char, mut handle: *cpp.stat): int
-
 cpp unsafe fn opendir(path: *Char): *cpp.DIR
 cpp unsafe fn closedir(mut dir: *cpp.DIR): int
 cpp unsafe fn readdir(mut dir: *cpp.DIR): *cpp.dirent
@@ -38,13 +32,13 @@ pub type Dir: cpp.DIR
 // C's dirent.
 pub type Dirent: cpp.dirent
 
-pub static STDIN: uintptr  = 0
+pub static STDIN: uintptr = 0
 pub static STDOUT: uintptr = 1
 pub static STDERR: uintptr = 2
 
 // Calls C's stat function.
 pub unsafe fn stat(path: *byte, mut stat: *Stat): int {
-    ret cpp.__jule_stat((*Char)(path), stat)
+    ret integ::emit[int]("stat({}, {})", (*Char)(path), stat)
 }
 
 // Wrapper for C's open function.