- set clone_depth to 1. Otherwise, appveyor spends
  4.5 minutes for the "git clone" alone

- Use Ninja instead of msbuild, it is (a bit) faster

- do not compile perfschema, or dynamic plugins
  to save time on compilation, or test execution.

- use -DFAST_BUILD=1 to speedup build a little

- increase number of parallel jobs used in build and test.
- Exclude some slow tests from the main suite.