In ARM asm code, ensure that every ENTRY(foo) has a matching END(foo).
The EABI unwind info requires a .fnend for every .fnstart, and newer
binutils will complain about seeing two .fnstart in a row.  This change
allows newer tools to compile our code.

Reported by:	bapt
Reviewed by:	imp
Automatically prefault a limited number of mappings to resident pages in
shmat(2), just like mmap(2).

MFC after:	5 days
Sponsored by:	EMC / Isilon Storage Division
GIC (Cortex A's interrupt controller) supports up to 1020 IRQs.