Avoid integer error in TEST_BITOPS tests
If "1" is not 64 bits wide already, then "1 << i" will not actually
work.
This bug only affects the TEST_BITOPS code, and shouldn't matter for
the actual use of the timeout code (except if/when it causes this
test to fail).
Reported by dcb314@hotmail.com. Fix for bug 23583. Not adding a
changes file, since this code is never compiled into Tor.