In conditionvar_timeout test, wait for threads to timeout

[nmathewson]

Previously we just waited 200msec, which was not enough on slow/busy
systems.

Fixes bug 27073; bugfix on 0.2.6.3-alpha when the test was introduced.

[coveralls]

Pull Request Test Coverage Report for Build 4127

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1106 unchanged lines in 10 files lost coverage.
• Overall coverage increased (+0.08%) to 50.04%

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Files with Coverage Reduction	New Missed Lines	%
src/or/circuituse.c	1	1.11%
src/ext/trunnel/trunnel.c	1	34.48%
src/or/directory.h	3	50.0%
src/or/routerlist.h	3	0.0%
src/or/circuitstats.c	7	73.71%
src/or/protover.c	16	93.58%
src/common/tortls.c	22	96.76%
src/or/dns.c	147	16.06%
src/or/router.c	199	33.57%
src/or/control.c	707	16.97%

Totals
Change from base Build 2144:	0.08%
Covered Lines:	29435
Relevant Lines:	58823

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💛 - Coveralls

[nmathewson]

merged to master; marked for backport.

[teor2345]

Re-opening to get CI on a recent merge.