Allow for parent project to enable fortran.

cmake/CallbackSetupExtraOptions.cmake

@@ -64,8 +64,10 @@ MACRO(TRIBITS_REPOSITORY_SETUP_EXTRA_OPTIONS)
   IF(NOT "$ENV{${PROJECT_NAME}_ENABLE_Fortran}" STREQUAL "" )
      SET(${PROJECT_NAME}_ENABLE_Fortran $ENV{${PROJECT_NAME}_ENABLE_Fortran})
   ELSE()
-     # ensure fortran compiler is set on
-     SET(${PROJECT_NAME}_ENABLE_Fortran OFF)
+     IF(NOT DEFINED ${PROJECT_NAME}_ENABLE_Fortran)
+        # ensure fortran compiler is set on
+        SET(${PROJECT_NAME}_ENABLE_Fortran OFF)
+     ENDIF()
   ENDIF()
   # Set up radix cmake directory, used by default option scripts
   SET(radix_CMAKE_DIR "${radix_SOURCE_DIR}/cmake" CACHE PATH "")