Added default Eigen search path to support Eigen that comes with PCL

cmake/OpenCVFindLibsPerf.cmake

@@ -32,7 +32,7 @@ endif(WITH_CUDA)
 # --- Eigen ---
 if(WITH_EIGEN)
   find_path(EIGEN_INCLUDE_PATH "Eigen/Core"
-            PATHS /usr/local /opt /usr ENV ProgramFiles ENV ProgramW6432
+            PATHS /usr/local /opt /usr $ENV{EIGEN_ROOT}/include ENV ProgramFiles ENV ProgramW6432 
             PATH_SUFFIXES include/eigen3 include/eigen2 Eigen/include/eigen3 Eigen/include/eigen2
             DOC "The path to Eigen3/Eigen2 headers"
             CMAKE_FIND_ROOT_PATH_BOTH)