libc: make stdout and stderr functional

what were before one extern FILE* without reference now are opened by libc on program initialization, to point to /dev/console by default.

libs/libc/crt0.asm

@@ -3,6 +3,7 @@ section .text
 extern _init
 extern main
 extern _fini
+extern initialize_libc
 extern exit
 
 global _start
@@ -13,6 +14,8 @@ _start:
 	push rbp ; rbp=0
 	mov rbp, rsp
 
+	call initialize_libc
+
 	call _init
 
     mov rdi, 0 ; argc = 0

libs/libc/include/stdio.h

@@ -13,13 +13,15 @@ typedef struct
     int f_err;
 } FILE;
 
+extern FILE* __stderr;
+extern FILE* __stdout;
+#define stderr __stderr
+#define stdout __stdout
+
 #ifdef __cplusplus
 extern "C"
 {
 #endif
-
-    extern FILE* stderr;
-#define stderr stderr
     int fclose(FILE*);
     int fflush(FILE*);
     FILE* fopen(const char*, const char*);

libs/libc/src/init.cpp

@@ -0,0 +1,14 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+extern "C" void initialize_libc()
+{
+    __stderr = fopen("/dev/console", "rw");
+    if (!stderr) exit(errno);
+    __stdout = fopen("/dev/console", "rw");
+    if (!stdout) exit(errno);
+    clearerr(__stderr);
+    clearerr(__stdout);
+}