perf: Correct the substitution of python shebangs

To make the native python3 always used,

- Use sed one-liner instead
- Add substitution for ${S}/scripts/bpf_helpers_doc.py to fix the
  following warning.

File "/usr/lib/python3.6/sysconfig.py", line 421, in _init_posix
_temp = __import__(name, globals(), locals(), ['build_time_vars'], 0)
ModuleNotFoundError: No module named '_sysconfigdata'

This issue is first reported by Joel Stanley <joel@jms.id.au>
The sed one-liner is credited to Anuj Mittal <anuj.mittal@intel.com>

(From OE-Core rev: 3f93173130a94310255389cfc62c67102a4fb21b)

(From OE-Core rev: c0bcc24ccc6d769935d7fa202a1405250d94e342)

Signed-off-by: He Zhe <zhe.he@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 3a1a18ba9d)
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-kernel/perf/perf.bb

@@ -233,11 +233,8 @@ do_configure_prepend () {
     fi
 
     # use /usr/bin/env instead of version specific python
-    for s in `find ${S}/tools/perf/ -name '*.py'`; do
-        sed -i 's,/usr/bin/python,/usr/bin/env python3,' "${s}"
-        sed -i 's,/usr/bin/python2,/usr/bin/env python3,' "${s}"
-        sed -i 's,/usr/bin/env python2,/usr/bin/env python3,' "${s}"
-        sed -i 's,/usr/bin/python3,/usr/bin/env python3,' "${s}"
+    for s in `find ${S}/tools/perf/ -name '*.py'` `find ${S}/scripts/ -name 'bpf_helpers_doc.py'`; do
+        sed -i -e "s,#!.*python.*,#!${USRBINPATH}/env python3," ${s}
     done
 
     # unistd.h can be out of sync between libc-headers and the captured version in the perf source