tests/unit/test-throttle: Avoid unintended integer division

tests/unit/test-throttle: Avoid unintended integer division

In test_compute_wait() we do
 double units = bkt.max / 10;
which does an integer division and then assigns it to a double variable,
and similarly later on in the expression for an assertion.

Use 10.0 so that we do a floating point division and calculate the
exact value, rather than doing an integer division.

Spotted by Coverity.

Resolves: Coverity CID 1432564
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20240312183810.557768-7-peter.maydell@linaro.org