Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

- Reimplement {d,i}tlb_enter() and {d,i}tlb_va_to_pa() in C. There's
no particular reason for them to be implemented in assembler and
having them in C allows easier extension as well as using more C
macros and {d,i}tlb_slot_max rather than hard-coding magic (and
actually spitfire-only) values.
- Fix the compilation of pmap_print_tte().
- Change pmap_print_tlb() to use ldxa() rather than re-rolling it
inline as well as TLB_DAR_SLOT and {d,i}tlb_slot_max rather than
hardcoding magic (and actually spitfire-only) values.
- While at it, suffix the above mentioned functions with "_sun4u" to
underline they're architecture-specific.
- Use __FBSDID and macros instead of magic values in locore.S.
- Remove unused includes and smp_stack in locore.S.

Start each of the license/copyright comments with /*-

Use a contrived 'tlb_entry' structure for passing the mappings for the
kernel text and data from the loader to the kernel, so that the tte format
is not part of the loader->kernel ABI.

Do not use semi-fixed TLB slots for the 4M kernel pages any more.

Keep track of the ttes used to map the kernel and pass them to it as loader
metadata. Modify tlb handling functions to take a tte, instead of virtual
address, physical address and flags.

Allocate a frame on our initial stack so that it doesn't run off into
random memory. Disable interrupts while loading the tlb.

Submitted by: tmm

Use ENTRY() for defining functions in asm.
Remove asm functions to call the openfirmware and kernel entry points;
we can just call them directly.
Don't use the stack pointer for an intermediate result in setx.
Put the stack in the bss.

Add the FreeBSD/sparc64 boot loader source files.