tcp: make CUBIC the default congestion control mechanism.

This changes the default TCP Congestion Control (CC) to CUBIC.
For small, transactional exchanges (e.g. web objects <15kB), this
will not have a material effect. However, for long duration data
transfers, CUBIC allocates a slightly higher fraction of the
available bandwidth, when competing against NewReno CC.

Reviewed By: tuexen, mav, #transport, guest-ccui, emaste
Relnotes: Yes
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D36537

sys/arm/conf/DEFAULTS

@@ -6,5 +6,5 @@
 device		mem
 
 # Default congestion control algorithm
-options 	CC_NEWRENO		# include newreno congestion control
+options 	CC_CUBIC		# include CUBIC congestion control
 

sys/arm/conf/std.armv6

@@ -8,8 +8,7 @@ options 	PREEMPTION		# Enable kernel thread preemption
 options 	VIMAGE			# Subsystem virtualization, e.g. VNET
 options 	INET			# InterNETworking
 options 	INET6			# IPv6 communications protocols
-options		CC_NEWRENO		# include newreno congestion control
-options		CC_DEFAULT=\"newreno\"	# define our default CC module it should be compiled in.
+options 	CC_CUBIC		# include CUBIC congestion control
 options 	TCP_HHOOK		# hhook(9) framework for TCP
 device		crypto			# core crypto support
 options 	IPSEC_SUPPORT		# Allow kldload of ipsec and tcpmd5

sys/arm/conf/std.armv7

@@ -8,8 +8,7 @@ options 	PREEMPTION		# Enable kernel thread preemption
 options 	VIMAGE			# Subsystem virtualization, e.g. VNET
 options 	INET			# InterNETworking
 options 	INET6			# IPv6 communications protocols
-options		CC_NEWRENO		# include newreno congestion control
-options		CC_DEFAULT=\"newreno\"	# define our default CC module it should be compiled in.
+options 	CC_CUBIC		# include CUBIC congestion control
 options 	TCP_HHOOK		# hhook(9) framework for TCP
 device		crypto			# core crypto support
 options 	IPSEC_SUPPORT		# Allow kldload of ipsec and tcpmd5