arm64: Save/restore TPIDR_EL0 in _arch_context_swap

It's not used for anything by the OS but userspace might want
to use it for its own purposes.

Change-Id: Icda4bcd6de9d68596555e81293c8bd075f80a2a4
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7511
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

kernel/arm64: implement iframe stack and unwinding

Change-Id: I1587c1f57bd73777a188bb8f1bc58263de82fcb9
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5684
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>
Reviewed-by: David Karoly <karolyd577@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>

arm64: Preserve FPU registers in setjmp/longjmp and arch_context_swap.

Change-Id: If0ca2ecbfa45b663dab39d1e9cb2562f071c3b27
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5268
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: David Karoly <karolyd577@gmail.com>
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

arm64: Implement kernel thread switching.

Change-Id: I87cca66ad89cfa85ba98a9ec828c5e357d7406b2
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5263
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>

ARM64: Add initial kernel headers

Signed-off-by: Augustin Cavalier <waddlesplash@gmail.com>
aarch64 -> arm64 and coding style fixes by me.