Normalize sourceroot path to prevent spurious warning

[olafurpg]

While testing locally on macOS against the directory netflix/hystrix I got the following warning

[error] semanticdb-javac: sourceroot '/Users/olafurpg/dev/netflix/hystrix does not contain path '/Users/olafurpg/dev/Netflix/Hystrix/hystrix-core/src/main/java/com/netflix/hystrix/strategy/HystrixArchaiusHelper.java'. To fix this problem, update the -sourceroot flag to be a parent directory of this source file.

The problem is that I had cloned the directory as Netflix/Hystrix and the SemanticDB compiler plugin is not correctly normalizing the sourceroot directory name before doing the startsWith check