perf tools: Check libaudit availability for perf-trace builtin

perf tools: Check libaudit availability for perf-trace builtin

The newly added trace command requires an external audit library.

However it can cause a build error because it's not checked whether the
libaudit is installed on system:

    CC builtin-trace.o
  builtin-trace.c:7:22: fatal error: libaudit.h: No such file or directory
  compilation terminated.
  make: *** [builtin-trace.o] Error 1

Signed-off-by: Namhyung Kim <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
[ committer note: Added ", disables 'trace tool' to the feature warning msg ]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>