Squashed 'evfibers/' changes from 1ff4825..96e7333

96e7333 Merge commit '1cf60c3ac6a7ef3b04aa149d93d5a94f5b13a4f8' into paxos-connector
4dee0e6 Added validating assertions for mutex calls

git-subtree-dir: evfibers
git-subtree-split: 96e7333aab5f8516272ec941f61b10e02c9f2c98
Merge commit '3e3b94474b04b927e9b25831575a5e15c9df7483'
Squashed 'evfibers/' changes from 96e7333..c5e30f6

c5e30f6 Fixed error with ASan when reclaiming self

git-subtree-dir: evfibers
git-subtree-split: c5e30f64b2832fddf0bbe8bc22de0125a3322847
Merge commit 'e1d4f08e3f03728d7eb3022c00a920323289615f'