perf tools: Remove support for command aliases

perf tools: Remove support for command aliases

This came from 'git', but isn't documented anywhere in
tools/perf/Documentation/, looks like baggage we can do without, ditch
it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-e7uwkn60t4hmlnwj99ba4t2s@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>