Rewrite init app in C, introduce MSL (MOP3 System Library)

kernel/amd64/syscall.c

@@ -6,7 +6,7 @@
 #include <proc/proc.h>
 #include <sys/debug.h>
 #include <sys/smp.h>
-#include <syscall/defs.h>
+#include <m/syscall_defs.h>
 #include <syscall/syscall.h>
 
 extern void amd64_syscall_entry (void);
@@ -14,8 +14,6 @@ extern void amd64_syscall_entry (void);
 int amd64_syscall_dispatch (void* stack_ptr) {
   struct saved_regs* regs = stack_ptr;
 
-  amd64_load_kernel_cr3 ();
-
   int syscall_num = regs->rax;
   syscall_handler_func_t func = syscall_find_handler (syscall_num);