[CMake] drop eigen version requirement

As on 16.04, /usr/lib/cmake/eigen3/Eigen3Config.cmake is not giving any.

Author: nim65s

CMakeLists.txt

@@ -40,7 +40,7 @@ COMPUTE_PROJECT_ARGS(PROJECT_ARGS LANGUAGES CXX)
 PROJECT(${PROJECT_NAME} ${PROJECT_ARGS})
 
 # Project dependencies
-ADD_PROJECT_DEPENDENCY(Eigen3 3.2.92 REQUIRED PKG_CONFIG_REQUIRES "eigen3 >= 3.2.92")
+ADD_PROJECT_DEPENDENCY(Eigen3 REQUIRED PKG_CONFIG_REQUIRES "eigen3 >= 3.2.92")
 SET(BOOST_COMPONENTS unit_test_framework)
 SEARCH_FOR_BOOST()