perf build: Get rid of VF_FEATURE_TESTS

perf build: Get rid of VF_FEATURE_TESTS

It only contains (FEATURE_TESTS - FEATURE_DISPLAY) tests to display the
rest of the checks on 'make VF=1'. But we can actually compute this
list, which is less confusing.

Also renaming LIB_FEATURE_TESTS into FEATURE_DISPLAY, so it reflects
what this variable actually does - display its tests status to user.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <david.ahern@oracle.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-gs160y03hpmx5ezpcr4gunxc@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>