Kernel: Remove includes to LibC stdarg definitions

We don't actually need the va_list and other stdarg definitions in the
kernel, because we actually don't use the "pure" printf interface in any
kernel code at all, but we retain the snprintf declaration because the
libstdc++ library still need it to be declared and extern'ed.

Kernel/kprintf.cpp

@@ -20,8 +20,6 @@
 #include <Kernel/TTY/ConsoleManagement.h>
 #include <Kernel/kstdio.h>
 
-#include <LibC/stdarg.h>
-
 namespace Kernel {
 extern Atomic<Graphics::Console*> g_boot_console;
 }
@@ -90,49 +88,13 @@ static void console_out(char ch)
     }
 }
 
-static void buffer_putch(char*& bufptr, char ch)
-{
-    *bufptr++ = ch;
-}
-
 // Declare it, so that the symbol is exported, because libstdc++ uses it.
 // However, *only* libstdc++ uses it, and none of the rest of the Kernel.
 extern "C" int sprintf(char* buffer, char const* fmt, ...);
 
-int sprintf(char* buffer, char const* fmt, ...)
+int sprintf(char*, char const*, ...)
 {
-    va_list ap;
-    va_start(ap, fmt);
-    int ret = printf_internal(buffer_putch, buffer, fmt, ap);
-    buffer[ret] = '\0';
-    va_end(ap);
-    return ret;
-}
-
-int snprintf(char* buffer, size_t size, char const* fmt, ...)
-{
-    va_list ap;
-    va_start(ap, fmt);
-    size_t space_remaining = 0;
-    if (size) {
-        space_remaining = size - 1;
-    } else {
-        space_remaining = 0;
-    }
-    auto sized_buffer_putch = [&](char*& bufptr, char ch) {
-        if (space_remaining) {
-            *bufptr++ = ch;
-            --space_remaining;
-        }
-    };
-    int ret = printf_internal(sized_buffer_putch, buffer, fmt, ap);
-    if (space_remaining) {
-        buffer[ret] = '\0';
-    } else if (size > 0) {
-        buffer[size - 1] = '\0';
-    }
-    va_end(ap);
-    return ret;
+    VERIFY_NOT_REACHED();
 }
 
 static inline void internal_dbgputch(char ch)