[kernel] Move the logger from kutil into kernel

Part one of a series of code moves. The kutil library is not very
useful, as most of its code is kernel-specific. This was originally for
testing purposes, but that can be achieved in other ways with the
current build system. I find this mostly creates a strange division in
the kernel code.

Instead, I'm going to move everything kernel-specific to actually be in
the kernel, and replace kutil with just 'util' for generic utility code
I want to share.

This commit:

- Moves the logger into the kernel.
- Updates the 'printf' library used from mpaland/printf to
  eyalroz/printf and moved it into the kernel, as it's only used by the
  logger in kutil.
- Removes some other unused kutil headers from some files, to help
  future code rearrangement.

Note that the (now redundant-seeming) log.cpp/h in kernel is currently
still there - these files are more about log output than the logging
system, and will get replaced once I add user-space log output.

src/kernel/interrupts.cpp

@@ -1,7 +1,7 @@
 #include <stdint.h>
 
 #include "kernel_memory.h"
-#include "kutil/printf.h"
+#include "printf/printf.h"
 
 #include "cpu.h"
 #include "device_manager.h"
@@ -130,7 +130,7 @@ isr_handler(cpu_state *regs)
                 break;
 
             snprintf(message, sizeof(message),
-                "Page fault: %016llx%s%s%s%s%s", cr2,
+                "Page fault: %016lx%s%s%s%s%s", cr2,
                 (regs->errorcode & 0x01) ? " present" : "",
                 (regs->errorcode & 0x02) ? " write" : "",
                 (regs->errorcode & 0x04) ? " user" : "",
@@ -153,7 +153,7 @@ isr_handler(cpu_state *regs)
         return;
 
     default:
-        snprintf(message, sizeof(message), "Unknown interrupt 0x%x", regs->interrupt);
+        snprintf(message, sizeof(message), "Unknown interrupt 0x%lx", regs->interrupt);
         kassert(false, message);
     }
 
@@ -170,7 +170,7 @@ irq_handler(cpu_state *regs)
     if (! device_manager::get().dispatch_irq(irq)) {
         char message[100];
         snprintf(message, sizeof(message),
-            "Unknown IRQ: %d (vec 0x%x)", irq, regs->interrupt);
+            "Unknown IRQ: %d (vec 0x%lx)", irq, regs->interrupt);
         kassert(false, message);
     }