This commit converts all of the CentOS 6.6 ports to support 32 or 64bit versions
It renames pkg-plist to pkg-plist.i686 for the existing files, and creates pkg-plist.x86_64
the original distinfo was already called distinfo.i686 so just creates distinfo.x86_64
To under with the 64bit version of CentOS instead of 32, in /etc/make.conf:
OVERRIDE_LINUX_BASE_PORT=c6_64