Static build can't find LIBSSH2 starting at v31.6.0 #871

$ apt list --installed | grep libssh
libssh2-1/now 1.8.0-1 amd64 [installed,local]
libssh2-1-dev/now 1.8.0-1 amd64 [installed,local]
$ git clone https://github.com/libgit2/git2go && cd git2go
$ git checkout v31.5.3 && git submodule update --init
$ make install-static # this works
$ rm -rf static-build
$ git checkout v31.6.0 && git submodule update --init # it's the same libgit2 anyways
$ make install-static
...
LIBSSH2 not found. Set CMAKE_PREFIX_PATH if it is installed outside of the default search path.
...