perf tools: Convert to BACKTRACE_SUPPORT

For building perf without stack backtrace debug, we can set
NO_BACKTRACE=1 as a argument of make.  It then defines NO_BACKTRACE
macro for C code to do the proper handling.  However it usually used in
a negative semantics - e.g. #ifndef - so we saw double negations which
can be misleading.  Convert it to a positive form to make it more
readable and add _SUPPORT suffix for consistency.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Irina Tirdea <irina.tirdea@gmail.com>
Cc: Irina Tirdea <irina.tirdea@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1349109171-1942-1-git-send-email-namhyung@kernel.org


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