Enabling linux64 packages by default on amd64

[Tijl Coosemans]

Hi,

With FreeBSD 9, 10.1 and 10.2 going EoL it's time to enable 64 bit Linux
packages by default on amd64.  If there are no objections I'd like to
flip the switch next week.

For now just change LINUX_DEFAULT to c6_64 so users can easily switch
back to 32 bit if there's a problem.  In a year or so we can remove
"c6_64" and "c7_64" and let "c6" and "c7" install 64 bit packages on
amd64.

Index: Mk/bsd.default-versions.mk
===================================================================
--- Mk/bsd.default-versions.mk	(revision 430716)
+++ Mk/bsd.default-versions.mk	(working copy)
@@ -42,7 +42,11 @@ GCC_DEFAULT?=		4.9
 # Possible values: 7, 8, 9, agpl
 GHOSTSCRIPT_DEFAULT?=	agpl
 # Possible values: c6, c6_64, c7, c7_64
+.if ${ARCH} == amd64
+LINUX_DEFAULT?=		c6_64
+.else
 LINUX_DEFAULT?=		c6
+.endif
 .if defined(OVERRIDE_LINUX_BASE_PORT)
 LINUX_DEFAULT:=		${OVERRIDE_LINUX_BASE_PORT}
 WARNING+=		"OVERRIDE_LINUX_BASE_PORT is deprecated, please use DEFAULT_VERSIONS+=linux=${OVERRIDE_LINUX_BASE_PORT}."


And PORTREVISION bumps of course.