Skip polyrec, etc. when templating from a sample

[Chris Warburton]

We can choose a sample and turn it into a template, with functions,
datatypes, etc. but we'll get errors if we try to look up the type of
functions that we've filtered out, e.g.

> Couldn't get type of 'global746970323031352f706f6c797265635f7365715f696e6465782e736d743266726f6d4c697374'
> Name 'global746970323031352f706f6c797265635f7365715f696e6465782e736d743266726f6d4c697374' is needed but wasn't found in '/nix/store/9mxryfmwmm2lxkhzs1m99a0flkn368wr-tebenchmark-data.json'
> builder for â??/nix/store/xdwx6h3q9zz4pk1cpm7l8m5vkfhvf6m7-functions-choose-100-0.drvâ?? failed with exit code 1

This decodes to:

    $ echo 'global746970323031352f706f6c797265635f7365715f696e6465782e736d743266726f6d4c697374' | decode
    tip2015/polyrec_seq_index.smt2fromList