tce-load -i compiletc openssl-dev

cd libssh2-1.8.0

CC="gcc -flto -fuse-linker-plugin -mtune=generic -Os -pipe" CXX="g++ -flto -fuse-linker-plugin -mtune=generic -Os -pipe -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local --disable-static --localstatedir=/var

find . -name Makefile -type f -exec sed -i 's/-g -O2//g' {} \;

make
sudo make install

  version:          1.8.0
  Host type:        x86_64-unknown-linux-gnu
  Install prefix:   /usr/local
  Compiler:         gcc -flto -fuse-linker-plugin -mtune=generic -Os -pipe
  Compiler flags:   -g -O2
  Library types:    Shared=yes, Static=no
  Crypto library:   OpenSSL (AES-CTR: yes)
  Clear memory:     unsupported
  Debug build:      no
  Build examples:   yes
  Path to sshd:     /usr/local/sbin/sshd (only for self-tests)
  zlib compression: yes