kernel/x86_64: Add errata patching.

The patched errata are only the AMD ones FreeBSD patches
(it seems there are no Intel errata that can be patched
this way, they are all in microcode updates ... or can't
be patched in the CPU at all.)

This also seems to be roughly the point in the boot that
FreeBSD patches these, too, despite how "critical" some
of them seem.

Change-Id: I9065f8d025332418a21c2cdf39afd7d29405edcc
Reviewed-on: https://review.haiku-os.org/c/haiku/+/1740
Reviewed-by: Jessica Hamilton <[email protected]>

headers/private/kernel/arch/x86/arch_cpu.h

@@ -557,6 +557,8 @@ void __x86_setup_system_time(uint32 conversionFactor,
 	uint32 conversionFactorNsecs, bool conversionFactorNsecsShift);
 #endif
 
+status_t __x86_patch_errata_percpu(int cpu);
+
 void x86_userspace_thread_exit(void);
 void x86_end_userspace_thread_exit(void);