security/libssh2: Update to 1.9.0
- Switch to CMake build system
- Remove post-patch steps which are resolved by the switch to CMake
- Add patches to ensure libssh2.pc is correct for ssl=base
- Switch to GitHub, since 1.9.0 tarball was missing files [1]
- Remove local patches which added support for ECDSA key exchange and SHA256 MAC - these are now included upstream (along with ED25519)
Changes this release:
https://www.libssh2.org/changes.html#1.9.0