Tweak suppressions file slightly to work with valgrind 3.7.0

Refs #3547
No spinning
refs #3752
Fixed unused variables.  Fixes #3749.

One of the unused variables was actually a bug... ooops
Merge pull request #3755 from WilkAndy/unused_3749

Fixed unused variables.  Fixes #3749.
Merge pull request #3753 from permcody/dmake

No spinning