Fortran: Test that CMAKE_Fortran_COMPILER_VERSION is set (#15372)

Update the CMakeOnly.CompilerIdFortran test to require that the variable
is set instead of just warning.  We already require it for C and CXX.

Tests/CMakeOnly/CompilerIdFortran/CMakeLists.txt

@@ -4,19 +4,11 @@ project(CompilerIdFortran Fortran)
 foreach(v
     CMAKE_Fortran_COMPILER
     CMAKE_Fortran_COMPILER_ID
-    )
-  if(${v})
-    message(STATUS "${v}=[${${v}}]")
-  else()
-    message(SEND_ERROR "${v} not set!")
-  endif()
-endforeach()
-foreach(v
     CMAKE_Fortran_COMPILER_VERSION
     )
   if(${v})
     message(STATUS "${v}=[${${v}}]")
   else()
-    message(WARNING "${v} not set!")
+    message(SEND_ERROR "${v} not set!")
   endif()
 endforeach()