perf build: Rename display_lib into feature_display

Preparing for feature checks separation, moving related stuff under
'feature*' namespace.

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-t72o4nwx81owjv14y43b2wpf@git.kernel.org


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