delay_timer rebuilds every time.

[chaaz]

Describe the bug
When cargo build is run on a project that depends on delay-timer, it will always rebuild, even if no changes have been made.

To Reproduce
Steps to reproduce the behavior:

1. Create a new project with cargo new --bin test_proj
2. Add delay_timer = "0.9.0" to the dependencies section of Cargo.toml
3. Run cargo build multiple times in succession

Every time cargo build is run, both delay_timer and the test_proj itself are recompiled.

Expected behavior
cargo build should not recompile anything if there have been no changes since the last compile.

Screenshots
N/A

Desktop (please complete the following information):

• OS: ubuntu 20
• delay_timer version: 0.9.0

[chaaz]

I've include a PR #23 which I think fixes the problem.

[BinChengZhao]

Hi, friends @chaaz

Thanks a lot for your feedback!

This may be caused by the fact that Cargo works differently on different operating systems, I did not see any abnormalities with the Mac-OS test.

But after testing, modifying build.rs also doesn't cause any problems with the existing compilation.

I decided to adopt PR, thanks for your feedback, this can affect Ubutun users a lot!

If there are any more questions or any suggestions on the project, feel free to contact me, thanks for your support suggestions!