test/time: no need to abs(uint64_t) for comparing

[tchaikov]

fixes

/home/kefu/dev/ceph/src/test/common/test_time.cc: In instantiation of
‘void system_clock_conversions() [with Clock =
ceph::time_detail::real_clock]’:
/home/kefu/dev/ceph/src/test/common/test_time.cc:134:40:   required from
here
/home/kefu/dev/ceph/src/test/common/test_time.cc:125:169: error: call of
overloaded ‘abs(std::chrono::duration<long unsigned int, std::ratio<1l,
1000000000l> >::rep)’ is ambiguous
   ASSERT_LT(abs((Clock::from_double(bd) - brt).count()), 30);

as std::abs() in libstdc++ shipped with gcc 6 does not have a specialization for unsigned types, and we
are using uint64_t as the typename duration<>::rep.

Signed-off-by: Kefu Chai kchai@redhat.com

[adamemerson]

This change looks fine to me.

[liewegas]

@tchaikov I reverted this since it broke the unittest:

[==========] Running 4 tests from 2 test cases.
[----------] Global test environment set-up.
[----------] 2 tests from RealClock
[ RUN ] RealClock.Sanity
[ OK ] RealClock.Sanity (0 ms)
[ RUN ] RealClock.Conversions
test/common/test_time.cc:125: Failure
Expected: ((Clock::from_double(bd) - brt).count()) < (30U), actual: 18446744073709551595 vs 30
[ FAILED ] RealClock.Conversions (0 ms)
[----------] 2 tests from RealClock (0 ms total)

[----------] 2 tests from CoarseRealClock
[ RUN ] CoarseRealClock.Sanity
[ OK ] CoarseRealClock.Sanity (0 ms)
[ RUN ] CoarseRealClock.Conversions
test/common/test_time.cc:125: Failure
Expected: ((Clock::from_double(bd) - brt).count()) < (30U), actual: 18446744073709551595 vs 30
[ FAILED ] CoarseRealClock.Conversions (0 ms)
[----------] 2 tests from CoarseRealClock (0 ms total)

[----------] Global test environment tear-down
[==========] 4 tests from 2 test cases ran. (0 ms total)
[ PASSED ] 2 tests.
[ FAILED ] 2 tests, listed below:
[ FAILED ] RealClock.Conversions
[ FAILED ] CoarseRealClock.Conversions

4c97aac