Set <Project>_ENABLE_Fortran=OFF by default for WIN32 (TriBITSPub#299)

It is very hard to get a Fortran compiler for native Windows so do everyone a
favor and just disable it by default for WIN32.

tribits/ReleaseNotes.txt

@@ -2,6 +2,12 @@
 Release Notes for TriBITS
 ----------------------------------------
 
+2021/11/18:
+
+(*) MAJOR: The default value for <Project>_ENABLE_Fortran is set to OFF on
+    WIN32 systems.  (Getting a Fortran compiler for native Windows is not
+    typically very easy.)
+
 2021/10/11:
 
 (*) MAJOR: The `<Package>Config.cmake` for each enabled package generated in

tribits/core/package_arch/TribitsGlobalMacros.cmake

@@ -291,7 +291,11 @@ macro(tribits_define_global_options_and_define_extra_repos)
   set(${PROJECT_NAME}_ENABLE_CXX11 ON)
 
   if ("${${PROJECT_NAME}_ENABLE_Fortran_DEFAULT}" STREQUAL "")
-    set(${PROJECT_NAME}_ENABLE_Fortran_DEFAULT ON)
+    if (WIN32)
+      set(${PROJECT_NAME}_ENABLE_Fortran_DEFAULT OFF)
+    else()
+      set(${PROJECT_NAME}_ENABLE_Fortran_DEFAULT ON)
+    endif()
   endif()
 
   option(${PROJECT_NAME}_ENABLE_Fortran

tribits/doc/guides/TribitsCoreDetailedReference.rst

@@ -368,6 +368,10 @@ These options are described below.
 
   This default can be set in `<projectDir>/ProjectName.cmake`_ or `<projectDir>/CMakeLists.txt`_.
 
+  On WIN32 sytems, the default for ``${PROJECT_NAME}_ENABLE_Fortran_DEFAULT``
+  is set to ``OFF`` since it can be difficult to get a Fortran compiler for
+  native Windows.
+
   Given that a native Fortran compiler is not supported by default on Windows
   and on most Mac OSX systems, projects that have optional Fortran code may
   decide to set the default depending on the platform by setting, for example::