Edge case with deps.plt

[joedevivo]

sometimes deps.plt doesn't get generated. I thought for sure that we'd resolved this when we added the recursive $(MAKE) call to the all target.

Even if it didn't get generated because make dialyzer was run before get-deps, running make all should get deps and then spawn the recursive make that build deps.plt.

@metadave had to delete his deps dir and make clean to get deps.plt to generate.

this could have been a bad state left by an older version of concrete, but the only state it's really ever had was .concrete/DEV_MODE so I'm perplexed by this