Make sure CPodeFree() does not call cpFreeVectors() unless initialization occurred.

[carmichaelong]

This was the smallest change I could see to address #641. Although the flag (cp_MallocDone) is not specifically set to true right when the vectors are allocated, I think this still follows the intention/flow of the code.

@chrisdembia @sherm1

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This change is 

[codecov-io]

Codecov Report

Merging #642 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #642      +/-   ##
==========================================
- Coverage   49.31%   49.31%   -0.01%     
==========================================
  Files         554      554              
  Lines       71104    71105       +1     
==========================================
- Hits        35067    35066       -1     
- Misses      36037    36039       +2

Impacted Files	Coverage Δ
...ntegrators/src/CPodes/sundials/src/cpodes/cpodes.c	57.08% <100%> (ø)	⬆️
SimTKcommon/BigMatrix/src/MatrixHelper.cpp	67.31% <0%> (-0.17%)	⬇️
SimTKmath/Optimizers/src/c-cmaes/cmaes.c	52.02% <0%> (-0.07%)	⬇️

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[sherm1]

Thanks, @carmichaelong and @chrisdembia !

Reviewed 1 of 1 files at r1.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @carmichaelong)

[sherm1]

@chrisdembia you have a blocking comment.

Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @carmichaelong)

[chrisdembia]

Reviewable status: complete! all files reviewed, all discussions resolved