ENH: actually keep the output

Source/CMakeLists.txt

@@ -1016,7 +1016,7 @@ IF(BUILD_TESTING)
     EXECUTE_PROCESS(COMMAND ${CMAKE_TEST_MAKEPROGRAM} --version
       RESULT_VARIABLE res OUTPUT_VARIABLE out
       ERROR_QUIET
-      OUTPUT_QUIET)
+      )
     IF("${res}" EQUAL 0)
       IF("${out}" MATCHES "GNU")
         SET(MAKE_IS_GNU 1)