Performance testing for fasta-dependent shootouts

Enable performance testing for fasta-dependent shootouts.

Each of these benchmarks takes as input the file generated by the fasta benchmark. They are all given a PREEXEC file that generates the input file sizes needed, and places them in test/tmp. This script will only run during a performance run, and will only generate files if they don't already exist. start_test will attempt to remove the test/tmp folder at the end of its script.
It seems like this could cause a problem in parallel testing.  I can see a situation where regex-dna checks that fasta.big exists, sees that it does and then attempts to use fasta.mid, when fasta.mid is not created yet.  I think either the test should be on the existence of each individual portion (see below), or it should be on the last file created by this if statement.

For instance (in pseudocode)
if tmpFasta doesn't exist and fasta.big or fasta.mid don't exist, create tmpFasta.
if fasta.big doesn't exist, create it.
if fasta.mid doesn't exist, create it.
if fasta.mid and fasta.big exist, remove tmpFasta.