Ensure gfortran compiler before checking version

Author: Damian Rouson

src/tests/unit/CMakeLists.txt

@@ -4,10 +4,12 @@ if (${opencoarrays_aware_compiler})
   add_subdirectory(init_register)
   add_subdirectory(collectives)
   add_subdirectory(sync)
-  if(NOT CMAKE_Fortran_COMPILER_VERSION VERSION_LESS 7)
-    add_subdirectory(fail_images)
-    if(NOT CMAKE_Fortran_COMPILER_VERSION VERSION_LESS 8)
-      add_subdirectory(teams)
+  if (gfortran_compiler)
+    if(NOT CMAKE_Fortran_COMPILER_VERSION VERSION_LESS 7)
+      add_subdirectory(fail_images)
+      if(NOT CMAKE_Fortran_COMPILER_VERSION VERSION_LESS 8)
+        add_subdirectory(teams)
+      endif()
     endif()
   endif()
 else()