[!761] [cmake] Use actual build program for Fortran test

Merge branch 'feature/support-manually-set-ninja-in-fortran-test' into 'master'

ref:core/dune-common Prior to this change the build program (make, Ninja) was
not identical to the one used by CMake, but the one installed on the system.

I found this when testing Fortran support of upcoming CMake 3.17 with upcoming
Ninja 1.10 - which works!

See merge request [core/dune-common!761]

  [core/dune-common!761]: gitlab.dune-project.org/core/dune-common/merge_requests/761

cmake/modules/LanguageSupport.cmake

@@ -33,7 +33,7 @@ function(workaround_9220 language language_works)
   file(WRITE ${CMAKE_BINARY_DIR}/language_tests/${language}/CMakeLists.txt
     ${text})
   execute_process(
-    COMMAND ${CMAKE_COMMAND} . -G "${CMAKE_GENERATOR}"
+    COMMAND ${CMAKE_COMMAND} . -G "${CMAKE_GENERATOR}" -DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}
     WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/language_tests/${language}
     RESULT_VARIABLE return_code
     OUTPUT_QUIET
@@ -43,7 +43,7 @@ function(workaround_9220 language language_works)
   if(return_code EQUAL 0)
     # Second run
     execute_process (
-      COMMAND ${CMAKE_COMMAND} .
+      COMMAND ${CMAKE_COMMAND} . -G "${CMAKE_GENERATOR}" -DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}
       WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/language_tests/${language}
       RESULT_VARIABLE return_code
       OUTPUT_QUIET