test/packaging: add test for cmake old style

.travis.yml

@@ -80,6 +80,12 @@ script:
   - cmake .. -DPYTHON_EXECUTABLE=$PYTHON_DEFAULT_VERSION 
   - make
   - ./extra_lib
+  - cd $TRAVIS_BUILD_DIR/unittest/packaging/cmake-2x
+  - mkdir build
+  - cd build
+  - cmake .. -DPYTHON_EXECUTABLE=$PYTHON_DEFAULT_VERSION 
+  - make
+  - ./extra_lib
   - cd $TRAVIS_BUILD_DIR/unittest/packaging/pkgconfig
   - export PKG_CONFIG_PATH=/tmp/_ci/install/lib/pkgconfig:$PKG_CONFIG_PATH
   - mkdir build

unittest/packaging/pkgconfig/CMakeLists.txt

+cmake_minimum_required(VERSION 2.6)
+
+project(ExtraLib CXX)
+find_package(PkgConfig REQUIRED)
+pkg_check_modules(EIGENPY REQUIRED eigenpy)
+find_package(PythonInterp REQUIRED)
+find_package(PythonLibs REQUIRED)
+
+include_directories(SYSTEM ${EIGENPY_INCLUDE_DIRS})
+add_executable(extra_lib extra_lib.cpp)
+target_link_libraries(extra_lib PUBLIC ${EIGENPY_LDFLAGS} ${PYTHON_LIBRARIES})

unittest/packaging/pkgconfig/extra_lib.cpp

+
+#include <eigenpy/version.hpp>
+
+int main(int /*argc*/, char ** /*argv*/)
+{
+  eigenpy::checkVersionAtLeast(0,0,0);
+  return 0;
+}