kernel/x86_64: AVX support

xsave or xsavec are supported.
breaks vregs compatibility.
change the thread structure object cache alignment to 64
the xsave fpu_state size isn't defined, it is for instance 832 here, thus I picked 1024.

Change-Id: I4a0cab0bc42c1d37f24dcafb8259f8ff24a330d2
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2849
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

kernel: support for Intel SMAP and SMEP on x86_64.

SMAP will generated page faults when the kernel tries to access user pages unless overriden.
If SMAP is enabled, the override instructions are written where needed in memory with
binary "altcodepatches".
Support is enabled by default, might be disabled per safemode setting.

Change-Id: Ife26cd765056aeaf65b2ffa3cadd0dcf4e273a96

kernel: Binary code patches on x86.

This will be used to support SMAP.

Sponsored-by: https://liberapay.com/korli