Kernel: Implement very simple kernel module loading

It's now possible to load a .o file into the kernel via a syscall.
The kernel will perform all the necessary ELF relocations, and then
call the "module_init" symbol in the loaded module.

Libraries/LibC/serenity.cpp

@@ -0,0 +1,19 @@
+#include <Kernel/Syscall.h>
+#include <errno.h>
+#include <serenity.h>
+
+extern "C" {
+
+int module_load(const char* path, size_t path_length)
+{
+    int rc = syscall(SC_module_load, path, path_length);
+    __RETURN_WITH_ERRNO(rc, rc, -1);
+}
+
+int module_unload(const char* name, size_t name_length)
+{
+    int rc = syscall(SC_module_unload, name, name_length);
+    __RETURN_WITH_ERRNO(rc, rc, -1);
+}
+
+}