[CMake] drop pkg-config

Author: nim65s

CMakeLists.txt

@@ -34,7 +34,7 @@ IF(BUILD_TESTING)
   FIND_PACKAGE(Boost REQUIRED COMPONENTS unit_test_framework)
 ENDIF()
 ADD_PROJECT_DEPENDENCY(Boost REQUIRED COMPONENTS serialization system thread)
-ADD_PROJECT_DEPENDENCY(Eigen3 REQUIRED PKG_CONFIG_REQUIRES eigen3)
+ADD_PROJECT_DEPENDENCY(Eigen3 REQUIRED)
 SEARCH_FOR_PTHREAD()
 
 IF(Boost_VERSION GREATER 107299 OR Boost_VERSION_MACRO GREATER 107299)