perf script python: Remove explicit shebang from tests/attr.c

tests/attr.c invokes attr.py via an explicit invocation of Python
($PYTHON) so there is therefore no need for an explicit shebang.

Also most distros follow pep-0394 which recommends that /usr/bin/python
refer only to v2 and so may not exist on the system (if PYTHON=python3).

Signed-off-by: Tony Jones <tonyj@suse.de>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Seeteena Thoufeek <s1seetee@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20190124005229.16146-5-tonyj@suse.de


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