Simplify recording of main thread's ID on MS-Windows

* src/w32term.c (w32_initialize):
* src/w32console.c (initialize_w32_display):
* src/w32fns.c (globals_of_w32fns): Don't record the main thread
ID independently for each type of session (GUI, TTY, batch).
* src/w32term.c (w32_init_main_thread): New function, records the
main thread's thread ID.
* src/w32term.h: Add prototype for w32_init_main_thread.
* src/emacs.c (main) [WINDOWSNT]: Call w32_init_main_thread.

* src/emacs-module.c [WINDOWSNT]: Rename main_thread_id to
main_thread, for consistency with other threading libraries.  All
users changed.  Include w32term.h.
(check_main_thread) [WINDOWSNT]: Simplify the test: no need to
make sure the main thread is alive, as we hold a handle on it
opened by w32_init_main_thread.
(module_init) [WINDOWSNT]: Reuse the thread ID recorded by
w32_init_main_thread, instead of calling the requisite APIs once
more.

1 files changed, 9 insertions, 4 deletions

diff --git a/src/w32term.c b/src/w32term.c
index f764e250aa8..f48e72553a5 100644
--- a/src/w32term.c
+++ b/src/w32term.c
@@ -6925,6 +6925,15 @@ x_delete_display (struct w32_display_info *dpyinfo)
 
 /* Set up use of W32.  */
 
+void
+w32_init_main_thread (void)
+{
+  dwMainThreadId = GetCurrentThreadId ();
+  DuplicateHandle (GetCurrentProcess (), GetCurrentThread (),
+                   GetCurrentProcess (), &hMainThread, 0, TRUE,
+                   DUPLICATE_SAME_ACCESS);
+}
+
 DWORD WINAPI w32_msg_worker (void * arg);
 
 static void
@@ -6985,10 +6994,6 @@ w32_initialize (void)
      terminates */
   init_crit ();
 
-  dwMainThreadId = GetCurrentThreadId ();
-  DuplicateHandle (GetCurrentProcess (), GetCurrentThread (),
-                   GetCurrentProcess (), &hMainThread, 0, TRUE, DUPLICATE_SAME_ACCESS);
-
   /* Wait for thread to start */
   {
     MSG msg;