Fix a bug introdiced in r217548.  According to NS DP83815 data
sheet, RX filter should be disabled before programming.
Previously it was clearing wrong bits so RX filter was not
disabled in RX filter configuration.

Reported by:	brad@OpenBSD.org
For level triggered interrupts clear the PIC IRR bit when the interrupt pin
is deasserted. Prior to this change each assertion on a level triggered irq
pin resulted in two interrupts being delivered to the CPU.

Differential Revision:	https://reviews.freebsd.org/D1310
Reviewed by:	tychon
MFC after:	1 week
sbin/shutdown: Support time units as in 'shutdown -r +5sec'

Units supported: s, sec, m, min, h, hour.

Differential Revision:	https://reviews.freebsd.org/D1272
Rename cpack*() to CMPLX*().

The C11 standard introduced a set of macros (CMPLX, CMPLXF, CMPLXL) that
can be used to construct complex numbers from a pair of real and
imaginary numbers. Unfortunately, they require some compiler support,
which is why we only define them for Clang and GCC>=4.7.

The cpack() function in libm performs the same task as CMPLX(), but
cannot be used to generate compile-time constants. This means that all
invocations of cpack() can safely be replaced by C11's CMPLX(). To keep
the code building with GCC 4.2, provide copies of CMPLX() that can at
least be used to generate run-time complex numbers.

This makes it easier to build some of the functions outside of libm.
Add missed break.

CID:	1258586
Sponsored by:	The FreeBSD Foundation
MFC after:	4 days
Add missed break.

CID:	1258587
Sponsored by:	The FreeBSD Foundation
MFC after:	20 days