Support using miniz_oxide for flate2 through feature flags

[jupyterkat]

it's annoying having to build a c lib, is there a reason why it's not used by default?

[blackbeam]

Hi.

As far as I remember of the two alternatives at that time one was significantly slower and another leads to mysql protocol errors. Anyway, you can use another flate2 backend:

[dependencies]
flate2 = { default-features = false, features = ["rust_backend"] }
mysql_common = { default-features = false, features = [ ] }
mysql = { default-features = false, features = [  ] }