Fix buffering issue

extra/io/unix/launcher/launcher.factor

@@ -77,7 +77,7 @@ USE: unix
 
         get-arguments exec-args-with-path
         (io-error)
-    ] [ 255 exit ] recover ;
+    ] [ 255 _exit "Exit failed" throw ] recover ;
 
 M: unix current-process-handle ( -- handle ) getpid ;
 

extra/unix/unix.factor

@@ -43,6 +43,7 @@ FUNCTION: int dup2 ( int oldd, int newd ) ;
 FUNCTION: int execv ( char* path, char** argv ) ;
 FUNCTION: int execvp ( char* path, char** argv ) ;
 FUNCTION: int execve ( char* path, char** argv, char** envp ) ;
+FUNCTION: int _exit ( int status ) ;
 FUNCTION: int fchdir ( int fd ) ;
 FUNCTION: int fchown ( int fd, uid_t owner, gid_t group ) ;
 FUNCTION: int fcntl ( int fd, int cmd, int arg ) ;