Disable static + thread-safe on Windows w/ CMake (HDFGroup#3622)

The thread-safety feature on Windows requires a hook in DllMain() and
thus is only available when HDF5 is built as a shared library.

This was previously a warning, but has now been elevated to a fatal
error that cannot be overridden with ALLOW_UNSUPPORTED.

Fixes GitHub HDFGroup#3613

CMakeLists.txt

@@ -863,8 +863,9 @@ option (HDF5_ENABLE_THREADSAFE "Enable thread-safety" OFF)
 if (HDF5_ENABLE_THREADSAFE)
   # check for unsupported options
   if (WIN32)
-    message (VERBOSE " **** thread-safety option not supported with static library **** ")
-    message (VERBOSE " **** thread-safety option will not be used building static library **** ")
+    if (BUILD_STATIC_LIBS)
+      message (FATAL_ERROR " **** thread-safety option not supported with static library **** ")
+    endif ()
   endif ()
   if (HDF5_BUILD_FORTRAN)
     if (NOT ALLOW_UNSUPPORTED)

release_docs/RELEASE.txt

@@ -47,7 +47,16 @@ New Features
 
     Configuration:
     -------------
-    -
+    - Thread-safety + static library disabled on Windows w/ CMake
+
+      The thread-safety feature requires hooks in DllMain(), which is only
+      present in the shared library.
+
+      We previously just warned about this, but now any CMake configuration
+      that tries to build thread-safety and the static library will fail.
+      This cannot be overridden with ALLOW_UNSUPPORTED.
+
+      Fixes GitHub issue #3613
 
 
     Library:
@@ -62,9 +71,6 @@ New Features
 
     Fortran Library:
     ----------------
-    -
-
-
     - Removed "-commons" linking option on Darwin, as COMMON and EQUIVALENCE
       are no longer used in the Fortran source.