tests: TimevalTest: refactor and avoid double comparison

Before this patch, the experession assert(then_secondws==then.seconds())
was failing in x86 architecture (and passing when adding a fprintf to
debug it). Avoid comparing the double values with == as that's usually a
bad idea, since the processor can output slightly different results for
the same operation depending on how it is optimized. Use timespec()
instead to check the invariant. Take the chance to refactor some
variables around to make the test easier to read.

Change-Id: Id4324be8ece86d371b1acb46bbd97856dfed241d
1 file changed