[PMC] Changed PMC destruction to free the PMC_sync structure only if it exists, which it never does.  This improves the primes.pasm benchmark by 1.3%.
[PMC] Changed PMC destruction to free the PMC_sync structure only if it exists,
which it never does.  This improves the primes.pasm benchmark by 1.3%.

git-svn-id: 6e74a02f85675cec270f5d931b0f6998666294a3@40982 d31e2699-5ff4-0310-a27c-f18f2fbe73fe

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