perf build: Display EXTRA features for VF=1 build

Display the state of the rest of the features (FEATURE_TESTS_EXTRA) on a
'make VF=1' build. These features are detected manually by perf's
Makefile.config so they can't be displayed with the main list, but only
after we're done in Makefile.config.

  $ make VF=1
    BUILD:   Doing 'make -j4' parallel build

  Auto-detecting system features:
  ...                         dwarf: [ on  ]
  ...            dwarf_getlocations: [ on  ]
  ...                         glibc: [ on  ]
  ...                          gtk2: [ on  ]

SNIP

  ...                       timerfd: [ on  ]
  ...                  sched_getcpu: [ on  ]
  ...                           sdt: [ on  ]
  ...                         setns: [ on  ]

extra features:
  ...                        bionic: [ OFF ]
  ...                    compile-32: [ on  ]
  ...                   compile-x32: [ OFF ]
  ...                cplus-demangle: [ on  ]
  ...                         hello: [ OFF ]
  ...                 libbabeltrace: [ on  ]
  ...                       liberty: [ on  ]
  ...                     liberty-z: [ on  ]
  ...         libunwind-debug-frame: [ OFF ]
  ...     libunwind-debug-frame-arm: [ OFF ]
  ... libunwind-debug-frame-aarch64: [ OFF ]

SNIP

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180109092646.GB11520@krava


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>