RUSTSEC-2019-0020: generator: fix unsound APIs that could lead to UB

Description

Affected versions of this crate API could use uninitialized memory with some APIs in special cases, like use the API in none generator context. This could lead to UB. The flaw was corrected by https://github.com/Xudong-Huang/generator-rs/issues/9 https://github.com/Xudong-Huang/generator-rs/issues/11 https://github.com/Xudong-Huang/generator-rs/issues/13 https://github.com/Xudong-Huang/generator-rs/issues/14
This patch fixes all those issues above.

More Info

https://github.com/Xudong-Huang/generator-rs/issues/9

Patched Versions