CE add mkdir command, implement create_dir () syscall

libsystem/system.c

@@ -78,3 +78,5 @@ int write_file (const char* path, size_t off, uint8_t* buffer, size_t size, uint
 int wait_for_pid (int pid) { return (int)do_syscall (SYS_WAIT_FOR_PID, pid); }
 
 int kill (int pid) { return (int)do_syscall (SYS_KILL, pid); }
+
+int create_dir (const char* path) { return (int)do_syscall (SYS_CREATE_DIR, path); }

libsystem/system.h

@@ -84,4 +84,7 @@ int wait_for_pid (int pid);
 /* Kill process */
 int kill (int pid);
 
+/* Create a directory */
+int create_dir (const char* path);
+
 #endif // _LIBMSL_M_SYSTEM_H