Exclude python scripts from RPM shebang check

Exclude python scripts from RPM shebang check

The newest Fedora packaging rules print warnings for scripts using the
/usr/bin/python shebang:

  *** WARNING: mangling shebang in /usr/src/spl-0.7.0/cmd/splslab/splslab.py
  from #!/usr/bin/python to #!/usr/bin/python2. This will become an ERROR,
  fix it manually!

Fedora wants all cross compatible scripts to pick python3.  Since we
don't want our users to have to pick a specific version of python, we
exclude our scripts from the RPM build check.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes: #699
Closes: #700