ntdll: Prefer a portable function to get thread id.

configure

@@ -10611,6 +10611,7 @@ LIBS="$LIBS $LIBPTHREAD"
 for ac_func in \
         pthread_attr_get_np \
         pthread_getattr_np \
+        pthread_getthreadid_np \
         pthread_get_stackaddr_np \
         pthread_get_stacksize_np
 do :

configure.ac

@@ -1471,6 +1471,7 @@ dnl **** Check for pthread functions ****
 WINE_CHECK_LIB_FUNCS(\
         pthread_attr_get_np \
         pthread_getattr_np \
+        pthread_getthreadid_np \
         pthread_get_stackaddr_np \
         pthread_get_stacksize_np,
         [$LIBPTHREAD])

dlls/ntdll/server.c

@@ -28,6 +28,9 @@
 #endif
 #include <errno.h>
 #include <fcntl.h>
+#ifdef HAVE_PTHREAD_NP_H
+# include <pthread_np.h>
+#endif
 #include <signal.h>
 #include <stdarg.h>
 #include <stdio.h>
@@ -944,7 +947,9 @@ static void send_server_task_port(void)
 static int get_unix_tid(void)
 {
     int ret = -1;
-#ifdef linux
+#ifdef HAVE_PTHREAD_GETTHREADID_NP
+    ret = pthread_getthreadid_np();
+#elif defined(linux)
     ret = syscall( SYS_gettid );
 #elif defined(__sun)
     ret = pthread_self();

include/config.h.in

@@ -632,6 +632,9 @@
 /* Define to 1 if you have the `pthread_getattr_np' function. */
 #undef HAVE_PTHREAD_GETATTR_NP
 
+/* Define to 1 if you have the `pthread_getthreadid_np' function. */
+#undef HAVE_PTHREAD_GETTHREADID_NP
+
 /* Define to 1 if you have the `pthread_get_stackaddr_np' function. */
 #undef HAVE_PTHREAD_GET_STACKADDR_NP