x86/entry: Make some entry symbols global

paranoid_entry(), error_entry() and xen_error_entry() have to be
exempted from call accounting by thunk patching because they are
before UNTRAIN_RET.

Expose them so they are available in the alternative code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111147.265598113@infradead.org