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.
- Nuke unused sdhci_softc.
- Static'ize sdhci_debug local to sdhci.c.
- Const'ify PCI device description strings.
- Nuke redundant resource ID members from sdhci_pci_softc.
- Nuke unused hw.sdhci_pci.debug tunable.
- Add support for using MSI instead of INTx, controllable via the tunable
  hw.sdhci.enable_msi (defaulting to on) and tested with a RICOH R5CE823 SD
  controller.
- Use NULL instead of 0 for pointers.

MFC after:	3 days
Compute sin(pi*x) without actually doing the pi*x multiplication.
sin_pi(x) is only called for x < 0 and |x| < 2**(p-1) where p is
the precision of x.  The new argument reduction is an optimization
compared to the old code, and it removes a chunk of dead code.
Accuracy tests in the intervals (-21,-20), (-20,-19), ... (-1,0)
show no differences between the old and new code.

Obtained from:	bde