CMake: Add a comment about threads on Cygwin.

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 13ff7b1cd1a7744d8946658c71315978353c7278..246d11a10606b5f69b358c7660cc35c9d7e26f4b 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -363,6 +363,7 @@ if(ENABLE_THREADS)
     find_package(Threads REQUIRED)
 
     # If both Windows and posix threading are available, prefer Windows.
+    # Note that on Cygwin CMAKE_USE_WIN32_THREADS_INIT is false.
     if(CMAKE_USE_WIN32_THREADS_INIT AND NOT ENABLE_THREADS STREQUAL "posix")
         if(ENABLE_THREADS STREQUAL "win95"
                 OR (ENABLE_THREADS STREQUAL "ON"