[init] Randomize load address of dynamic ELF modules

Update init to use the new xoroshiro RNG to create a random load address for dynamic executables.
Also pass an address past the end of the loader in the loader_arg to use when loading dynamic
dependencies.

src/libraries/j6/include/j6/init.h

@@ -42,6 +42,8 @@ struct j6_arg_loader
     uintptr_t image_base;
     uintptr_t *got;
     uintptr_t entrypoint;
+    uintptr_t start_addr;
+    uintptr_t other;
 };
 
 struct j6_arg_driver