perf tui: Only support --tui with slang

perf tui: Only support --tui with slang

Make the --tui command line flags dependent HAVE_SLANG_SUPPORT. This was
reported as confusing in:
https://lore.kernel.org/linux-perf-users/YevaTkzdXmFKdGpc@zx-spectrum.none/

Reported-by: xaizek <xaizek@posteo.net>
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: xaizek <xaizek@posteo.net>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20220123191849.3655855-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>