Add emulation for Intel e1000 (e82545) network adapter.

The code was successfully tested with FreeBSD, Linux, Solaris and Windows
guests.  This interface is predictably slower (about 2x) then virtio-net,
but it is very helpful for guests not supporting virtio-net by default.

Thanks to Jeremiah Lott and Peter Grehan for doing original heavy lifting.

usr.sbin/bhyve/Makefile

@@ -28,6 +28,7 @@ SRCS=	\
 	mevent.c		\
 	mptbl.c			\
 	pci_ahci.c		\
+	pci_e82545.c		\
 	pci_emul.c		\
 	pci_fbuf.c		\
 	pci_hostbridge.c	\
@@ -61,6 +62,8 @@ SRCS+=	vmm_instruction_emul.c
 
 LIBADD=	vmmapi md pthread z
 
+CFLAGS+= -I${BHYVE_SYSDIR}/sys/dev/e1000
+CFLAGS+= -I${BHYVE_SYSDIR}/sys/dev/mii
 CFLAGS+= -I${BHYVE_SYSDIR}/sys/dev/usb/controller
 
 WARNS?=	2

usr.sbin/bhyve/bhyve.8

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd July 8, 2016
+.Dd July 9, 2016
 .Dt BHYVE 8
 .Os
 .Sh NAME
@@ -177,6 +177,8 @@ AHCI controller attached to arbitraty devices.
 AHCI controller attached to an ATAPI CD/DVD.
 .It Li ahci-hd
 AHCI controller attached to a SATA hard-drive.
+.It Li e1000
+Intel e82545 network interface.
 .It Li uart
 PCI 16550 serial device.
 .It Li lpc