Move DO_AST into pcb.h where it should have been all along. Move some
common macros for saving/restoring registers into pcb.h as well.

Reviewed by:	jmallet@
Move DO_AST into pcb.h where it should have been all along. Move some
common macros for saving/restoring registers into pcb.h as well.
Replace uses of the ALEAF macro with XLEAF and remove ALEAF macro to
try to unify the conventions used in our assembler.

Reviewed by:	jmallet@
Replace NLEAF with LEAF_NOPROFILE to unify the conventions we use in
our assembler files.

Reviewed by:	jmallet@
Elminate NON_LEAF and use NESTED instead to unify our assembler
conventions.

Reviewed by:	jmallet@
- Fix "ifname|addr" syntax support in jail_{jname}_ip.
- Create /var/run/jail_{jname}.id because ezjail-admin depends on it.