perf tools: Add --tui and --stdio to choose the UI

Relying just on ~/.perfconfig or rebuilding the tool disabling support
for the TUI is too cumbersome, so allow specifying which UI to use and
make the command line switch override whatever is in ~/.perfconfig.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>