Merge pull request #89 from NervanaSystems/bob/eigen_build_fix

fix install directory name. not sure why it worked on osx, but who re…

cmake/external_eigen.cmake

@@ -11,8 +11,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-cmake_minimum_required(VERSION 3.7)
-
 # Enable ExternalProject CMake module
 include(ExternalProject)
 
@@ -36,4 +34,4 @@ ExternalProject_Add(
 
 ExternalProject_Get_Property(eigen source_dir binary_dir)
 
-set(EIGEN_INCLUDE_DIR "${EXTERNAL_INSTALL_LOCATION}/include/Eigen3" PARENT_SCOPE)
+set(EIGEN_INCLUDE_DIR "${EXTERNAL_INSTALL_LOCATION}/include/eigen3" PARENT_SCOPE)