Fix dtls regression #98

Job	Run time
run-checker (enable-asan enable-ubsan no-shared no-asm -DOPENSSL_SMALL_FOOTPRINT)	1m 48s
run-checker (no-ct)	1m 19s
run-checker (no-dso)	1m 19s
run-checker (no-dynamic-engine)	1m 29s
run-checker (no-engine no-shared)	1m 25s
run-checker (no-err)	1m 22s
run-checker (no-filenames)	1m 21s
run-checker (enable-ubsan no-asm -DOPENSSL_SMALL_FOOTPRINT -fno-sanitize=alignment)	1m 32s
run-checker (no-module)	1m 24s
run-checker (no-ocsp)	1m 20s
run-checker (no-pinshared)	1m 26s
run-checker (no-srp)	1m 25s
run-checker (no-srtp)	1m 20s
run-checker (no-ts)	1m 17s
run-checker (enable-weak-ssl-ciphers)	1m 21s
run-checker (enable-zlib)	1m 24s
	22m 32s

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