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.
- bsd.port.mk:
  - Move Linux related bits to Uses/linux.mk, except USE_LINUX_PREFIX.
  - Put USE_LINUX_PREFIX handling after USES processing.
  - Define DOCSDIR, DATADIR, etc. after handling USE_LINUX_PREFIX so it can
    give these variables a different default value.
  - When a package needs to run Linux ldconfig check before installation if
    Linux support is enabled.
- emulators/linux_base-*:
  - Use USES=linux and remove duplication.
  - Remove files/lp.  FreeBSD or CUPS lp(1) should work.
  - Remove files/yp.conf.  No longer seems to be used.
  - Remove pkg-deinstall and move pkg-install into pkg-plist.
  - Update pkg-descr and pkg-message.
  - Fix handling of ldconfig cache in pkg-plist.
- devel/fb-adb: Use a Linux shell to run a Linux script but patch the script
  to use FreeBSD mkdir so mkdir -p $path creates $path and not
  /compat/linux/$path.

PR:		211645
Exp-run by:	antoine
Approved by:	portmgr (antoine)