Optional CodeCoverage Building Instrumentation

[Bob-Chen222]

Need to figure out a way to build the FlexFlow with code coverage instrumentation optionally.

[Bob-Chen222]

The easiest thing I can come up with now is that when the user calls proj make, two different build directories will come out. One is with instrumentation, and one is not. When the user calls proj test --coverage, it will run in the directory with coverage instrumentation. Otherwise, it will run in the original build repo. Do you think this would work? @lockshaw

[lockshaw]

I would recommend only building the with-instrumentation version when the user runs tests with coverage, as most of the time the user will not be examining the coverage information and we don't want to unnecessarily slow down most builds. Note that proj test already builds things that proj build does not (proj build does not build the test suites), so this isn't anything particularly new

[lockshaw]

Closed by #1396