Use libssh2 1.9.0 which has been fixed to compile with OpenSSL 1.1

See the release notes
https://github.com/libssh2/libssh2/blob/master/RELEASE-NOTES

Compilation should have failed since we upgraded OpenSSL.
It seems that they succeeded only because they did not happen.
That's because the result of previous compilation is cached.
The failure is differed until the cache is cleaned, which happens on regular time basis.
How fragile...

third-party/libssh2.spec

@@ -1,8 +1,8 @@
-libssh2_spec_download_url:=https://www.libssh2.org/download/libssh2-1.7.0.tar.gz		 
-libssh2_spec_archive_name:=libssh2-1.7.0.tar.gz
-libssh2_spec_unpack_dir_name:=libssh2-1.7.0
+libssh2_spec_download_url:=https://www.libssh2.org/download/libssh2-1.9.0.tar.gz		 
+libssh2_spec_archive_name:=libssh2-1.9.0.tar.gz
+libssh2_spec_unpack_dir_name:=libssh2-1.9.0
 libssh2_spec_product_name_macOS:=libssh2.1.dylib
 libssh2_spec_product_name_linux:=libssh2.so.1.0.1
 libssh2_spec_product_name_windows:=libssh2-1.dll
 libssh2_spec_symlinks_macOS:=libssh2*.dylib
-libssh2_spec_symlinks_linux:=libssh2.so*
+libssh2_spec_symlinks_linux:=libssh2.so*