multimedia/ffmpeg port test failure

[chukharev at mail.ru]

The 'port test' command (ports-mgmt/porttools) tests a port for a number of possible errors
by running portlint, building, packaging, installing, and de-installing with a check for
left files. This is done with defined PREFIX and PKG_DBDIR variables. 'port test' command
is recommended by the Porter's Handbook.

Note that the port installs the usual way.

When running 'port test' command in multimedia/ffmpeg, the following output is generated
indicating fatal errors from portlint.

multimedia/ffmpeg
+++++++++++++++

===> Validating port with portlint
FATAL: Makefile: [287]: contiguous blank lines (> 1 lines) found.
WARN: Makefile: [315]: use ${VARIABLE}, instead of $(VARIABLE).
WARN: Makefile: [247]: You may remove pkg-plist if you use PLIST_FILES and/or PLIST_DIRS.
WARN: Makefile: [34]: possible direct use of command "install" found. use ${INSTALL_foobaa} instead.
WARN: Makefile: only one MASTER_SITE configured.  Consider adding additional mirrors.
1 fatal error and 4 warnings found.
Error validating port