title: How to get static libraries for Eclipse Paho MQTT C client?
body: <p>I'm trying to compile the code from the <a href="https://github.com/eclipse/paho.mqtt.c" rel="nofollow noreferrer">Paho repository</a> on Ubuntu 16.04, such that the static libraries are produced:</p>
  
  <pre><code>cd ~/Downloads
  git clone https://github.com/eclipse/paho.mqtt.c.git
  mkdir /tmp/build.paho
  cd /tmp/build.paho
  cmake -GNinja -DPAHO_WITH_SSL=TRUE -DPAHO_BUILD_STATIC=TRUE ~/Downloads/paho.mqtt.c
  </code></pre>
  
  <p>The procedure always fails with the following errors:</p>
  
  <pre><code>-- The C compiler identification is GNU 5.4.0
  -- Check for working C compiler: /usr/bin/cc
  -- Check for working C compiler: /usr/bin/cc -- works
  -- Detecting C compiler ABI info
  -- Detecting C compiler ABI info - done
  -- Detecting C compile features
  -- Detecting C compile features - done
  -- CMake version: 3.5.1
  -- CMake system name: Linux
  -- Timestamp is 2019-10-22T09:16:51Z
  CMake Error at src/CMakeLists.txt:95 (ADD_LIBRARY):
    add_library cannot create target "paho-mqtt3c" because another target with the same name already exists.  The existing target is a shared library created in source directory "/home/&lt;username&gt;/Downloads/paho.mqtt.c/src".  See documentation for policy CMP0002 for more details.
  
  CMake Error at src/CMakeLists.txt:96 (ADD_LIBRARY):
    add_library cannot create target "paho-mqtt3a" because another target with the same name already exists.  The existing target is a shared library created in source directory "/home/&lt;username&gt;/Downloads/paho.mqtt.c/src".  See documentation for policy CMP0002 for more details.
  
  CMake Error at src/CMakeLists.txt:101 (INSTALL):
    install TARGETS given no LIBRARY DESTINATION for shared library target "paho-mqtt3c".
  
  -- OpenSSL hints: 
  -- OpenSSL headers found at /usr/include
  -- OpenSSL library found at /usr/lib/aarch64-linux-gnu/libssl.so
  -- OpenSSL Crypto library found at /usr/lib/aarch64-linux-gnu/libcrypto.so
  CMake Error at src/CMakeLists.txt:165 (ADD_LIBRARY):
    add_library cannot create target "paho-mqtt3cs" because another target with the same name already exists.  The existing target is a shared library created in source directory "/home/&lt;username&gt;/Downloads/paho.mqtt.c/src".  See documentation for policy CMP0002 for more details.
  
  CMake Error at src/CMakeLists.txt:166 (ADD_LIBRARY):
    add_library cannot create target "paho-mqtt3as" because another target with the same name already exists.  The existing target is a shared library created in source directory "/home/&lt;username&gt;/Downloads/paho.mqtt.c/src".  See documentation for policy CMP0002 for more details.
  
  CMake Error at src/CMakeLists.txt:176 (INSTALL):
    install TARGETS given no LIBRARY DESTINATION for shared library target "paho-mqtt3cs".
  
  -- OpenSSL hints: 
  -- OpenSSL headers found at /usr/include
  -- Configuring incomplete, errors occurred!
  See also "/home/&lt;username&gt;/Downloads/paho.mqtt.c/build/CMakeFiles/CMakeOutput.log".
  </code></pre>
  
  <p>I don't understand what is going wrong. To my understanding I'm exactly following the steps of the repository documentation.</p>
  
  <p>What else do I have to do, or what do I need to do differently?</p>