kernel/arch: Make arch_debug_get_caller() a macro implemented by a builtin.

Only the x86 and PPC implementations look like they would have worked,
while the builtin is available and will work across all architectures.
We already use it unconditionally in some parts of libroot.

Change-Id: I2dffb3b2c7cdd605092382b9d649151adb921bb4
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6942
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

sparc: implement thread local storage support

The sparc ABI reserves the g7 register for this.

Change-Id: I93b81ecef72cde859972ef7b7f6b9991d35f9f29
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3583
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

kernel/arch/sparc: stubs to get the kernel to link

Add empty implementation of timer, elf, vm, debugger support, to let the
kernel link.

Also add the kernel linker script.

Change-Id: If0795fa6554aea3df1ee544c25cc4832634ffd78
Reviewed-on: https://review.haiku-os.org/c/1108
Reviewed-by: waddlesplash <waddlesplash@gmail.com>