Silence noisy firewire logging.

MFC after:	1 month
Sponsored by:	Spectra Logic
MFSpectraBSD:	974594 on 2013/08/02
When updating device media size use cached cdevsw pointer.

Using pointer from the cdev directly is dangerous since we have no reference
on it, and it may change any time.  That caused panic if device has gone.

While there, report capacity change only if it really changed.

MFC after:	3 days
Start the process of cleaning up FreeBSD's firewire driver.

sys/dev/firewire/firewire.c:
sys/dev/firewire/firewire.h:
sys/dev/firewire/firewirereg.h:
sys/dev/firewire/fwcrom.c:
sys/dev/firewire/fwdev.c:
sys/dev/firewire/fwdma.c:
sys/dev/firewire/fwmem.c:
sys/dev/firewire/fwohci.c:
sys/dev/firewire/fwohci_pci.c:
sys/dev/firewire/fwohcivar.h:
sys/dev/firewire/if_fwe.c:
sys/dev/firewire/if_fwip.c:
sys/dev/firewire/sbp.c:
sys/dev/firewire/sbp_targ.c:
	Unifdef the code, removing support for DragonflyBSD
	and FreeBSD prior to version 5.

Submitted by:	gibbs
MFC after:	1 month
Sponsored by:	Spectra Logic
MFSpectraBSD:	1081188 on 2014/08/01
Use 'cc' for the C compiler instead of 'gcc'.

MFC after:	1 week
Sponsored by:	Spectra Logic
MFSpectraBSD:	1079507 on 2014/07/24
Make kernel to update LUN size from the backing storage on configuration
reload also if that size was not specified in the new configuration.

Previously it happened only if size was explicitly changed in config.

MFC after:	3 days