Annotate the nights where NPB EP and IS performed better, used -E

I had misinterpretted the desire to use -E as a desire to use it nightly rather
than a desire to maintain default behavior but compare it to tweaked behavior.
Since there isn't a good way to compare them (our execenvs don't allow multiple
settings), decided to just leave the default for now.
Merge pull request #897 from lydia-duncan/annotateEOptionUse

Annotate the nights where NPB EP and IS performed better, used -E

I had misinterpretted the desire to use -E as a desire to use it nightly rather
than a desire to maintain default behavior but compare it to tweaked behavior.
Since there isn't a good way to compare them (our execenvs don't allow multiple
settings), we decided to just leave the default for now. Since that churn is
reflected in the nightly graphs, annotate it so we don't forget.

Note, the commit in question also affected FT, but for sizes we don't run nightly.