Update `things you can do` message using cmake commands

Print cmake commands instead of make commands, which should work for any generator.

CMakeLists.txt

@@ -529,32 +529,30 @@ message(STATUS "")
 
 string(TOLOWER "${CMAKE_GENERATOR}" cmake_generator_tolower)
 if(cmake_generator_tolower MATCHES "makefile")
-  message(STATUS "Some things you can do now:")
-  message(STATUS "--------------+--------------------------------------------------------------")
-  message(STATUS "Command       |   Description")
-  message(STATUS "--------------+--------------------------------------------------------------")
-  message(STATUS "make install  | Install Eigen. Headers will be installed to:")
-  message(STATUS "              |     <CMAKE_INSTALL_PREFIX>/<INCLUDE_INSTALL_DIR>")
-  message(STATUS "              |   Using the following values:")
-  message(STATUS "              |     CMAKE_INSTALL_PREFIX: ${CMAKE_INSTALL_PREFIX}")
-  message(STATUS "              |     INCLUDE_INSTALL_DIR:  ${INCLUDE_INSTALL_DIR}")
-  message(STATUS "              |   Change the install location of Eigen headers using:")
-  message(STATUS "              |     cmake . -DCMAKE_INSTALL_PREFIX=yourprefix")
-  message(STATUS "              |   Or:")
-  message(STATUS "              |     cmake . -DINCLUDE_INSTALL_DIR=yourdir")
-  message(STATUS "make doc      | Generate the API documentation, requires Doxygen & LaTeX")
-  if(BUILD_TESTING)
-    message(STATUS "make check    | Build and run the unit-tests. Read this page:")
-    message(STATUS "              |   http://eigen.tuxfamily.org/index.php?title=Tests")
-  endif()
-  message(STATUS "make blas     | Build BLAS library (not the same thing as Eigen)")
-  message(STATUS "make uninstall| Removes files installed by make install")
-  message(STATUS "--------------+--------------------------------------------------------------")
+  message(STATUS "Available targets (use: make TARGET):")
 else()
-  message(STATUS "To build/run the unit tests, read this page:")
-  message(STATUS "  http://eigen.tuxfamily.org/index.php?title=Tests")
+  message(STATUS "Available targets (use: cmake . --build --target TARGET):")
 endif()
-
+message(STATUS "---------+--------------------------------------------------------------")
+message(STATUS "Target   |   Description")
+message(STATUS "---------+--------------------------------------------------------------")
+message(STATUS "install  | Install Eigen. Headers will be installed to:")
+message(STATUS "         |     <CMAKE_INSTALL_PREFIX>/<INCLUDE_INSTALL_DIR>")
+message(STATUS "         |   Using the following values:")
+message(STATUS "         |     CMAKE_INSTALL_PREFIX: ${CMAKE_INSTALL_PREFIX}")
+message(STATUS "         |     INCLUDE_INSTALL_DIR:  ${INCLUDE_INSTALL_DIR}")
+message(STATUS "         |   Change the install location of Eigen headers using:")
+message(STATUS "         |     cmake . -DCMAKE_INSTALL_PREFIX=yourprefix")
+message(STATUS "         |   Or:")
+message(STATUS "         |     cmake . -DINCLUDE_INSTALL_DIR=yourdir")
+message(STATUS "doc      | Generate the API documentation, requires Doxygen & LaTeX")
+if(BUILD_TESTING)
+  message(STATUS "check    | Build and run the unit-tests. Read this page:")
+  message(STATUS "         |   http://eigen.tuxfamily.org/index.php?title=Tests")
+endif()
+message(STATUS "blas     | Build BLAS library (not the same thing as Eigen)")
+message(STATUS "uninstall| Remove files installed by the install target")
+message(STATUS "---------+--------------------------------------------------------------")
 message(STATUS "")