Drop support for Linux Fedora 10 (ports part)
games/dsnake only worked with linux-f10

Should fix INDEX

audio/linux-f10-sdl_mixer
audio/linux-f10-pulseaudio-libs
audio/linux-f10-freealut
audio/linux-f10-arts
audio/linux-f10-esound
audio/linux-f10-libogg
audio/linux-f10-alsa-plugins-oss
audio/linux-f10-openal
audio/linux-f10-openal-soft
audio/linux-f10-nas-libs

- Replace Mk/bsd.linux-apps.mk and Mk/bsd.linux-rpm.mk with
  Mk/Uses/linux.mk.
- Replace USE_LINUX=yes with USES+=linux and USE_LINUX=(.*) with
  USES+=linux:\1 in all ports.
- Replace USE_LINUX_APPS with USE_LINUX in all ports.
- Use INSTALL_SCRIPT instead of INSTALL_PROGRAM to install scripts in some
  ports.
- When USE_LINUX_RPM is defined, simplify the way DISTFILES and EXTRACT_ONLY
  are defined.
- Remove BRANDELF_DIRS and BRANDELF_FILES handling.  In the very rare cases
  that it is still necessary ports can run ${BRANDELF} from post-patch.
- Remove AUTOMATIC_PLIST handling.  Only one port used it.
- Fix Linux MASTER_SITES.
- Replace OVERRIDE_LINUX_BASE_PORT and OVERRIDE_LINUX_NONBASE_PORTS with
  default versions framework.

Cleanup plist

Update CentOS base to 6.5, add userland ports

The Fedora 10 infrastructure ports have been in use since June 2009 and, while
having served a great deed, have become unsupported upstream and hence affected
by unfixed security vulnerabilities. In addition to that, many recent Linux
binaries need newer libc / stdlibc++ versions.

This commit adds the linux-c6- userland as drop-in replacement for the -f10
infrastructure, as well as upgrading the linux_base-c6 port to CentOS 6.5.

If you want to switch to linux-c6 ports, please define at /etc/make.conf:

    OVERRIDE_LINUX_BASE_PORT=c6
    OVERRIDE_LINUX_NONBASE_PORTS=c6