Bug#1082117: mlpack: Incorrect and missing dependencies

[Ryan Curtin]

I should also add that there is a recommended dependency of libstb-dev
for image processing support---if that's not installed, compiling
against mlpack will issue a warning.  So it's likely that should be
installed by default too.

-- 
Ryan Curtin    | "Don't fight it son. Confess quickly! If you hold out too
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