Ensure Process.ProcessName doesn't change when setting Thread.Name on…

… Linux

Fixes dotnet/runtime#33673

This issue is a side-effect of adding support for setting thread names on Linux in dotnet/coreclr#27182.

cc @janvorli @lpereira @SteveL-MSFT

mono/utils/mono-threads-posix.c

@@ -282,6 +282,15 @@ mono_native_thread_set_name (MonoNativeThreadId tid, const char *name)
 	if (tid != mono_native_thread_id_get ())
 		return;
 
+#if defined(__linux__)
+	/*
+	 * Ignore requests to set the main thread name because
+	 * it causes the value returned by Process.ProcessName to change.
+	 */
+	if (mono_native_thread_os_id_get () == (guint64)getpid ())
+		return;
+#endif
+
 	if (!name) {
 		pthread_setname_np ("");
 	} else {