Java directors - more generic thread name setting

Activated if a user sets SWIG_JAVA_USE_THREAD_NAME.
Implementations provided for linux/android/macos/unix.
A user's implementation will be used if SWIG_JAVA_GET_THREAD_NAME is
defined. It must implement the function:
  namespace Swig {
    SWIGINTERN int GetThreadName(char *name, size_t len);
  }

Examples/test-suite/director_thread.i

@@ -7,6 +7,11 @@
 %module(directors="1") director_thread
 #endif
 
+%begin %{
+#define SWIG_JAVA_USE_THREAD_NAME
+//#define DEBUG_DIRECTOR_THREAD_NAME
+%}
+
 %{
 #ifdef _WIN32
 #include <windows.h>
@@ -89,10 +94,23 @@ extern "C" {
         fprintf(stderr, "pthread_create failed in run()\n");
         assert(0);
       }
+      int setname = pthread_setname_np(thread, "MyThreadName");
+      if (setname != 0) {
+        fprintf(stderr, "pthread_setname_np failed in run()\n");
+        assert(0);
+      }
 %#endif
       MilliSecondSleep(500);
     }
-    
+
+    static bool namedThread() {
+%#ifdef _WIN32
+      return false;
+%#else
+      return true;
+%#endif
+    }
+
     virtual void do_foo() {
       val += 1;
     }

Examples/test-suite/java/director_thread_runme.java

@@ -30,6 +30,12 @@ class director_thread_Derived extends Foo {
   }
 
   public void do_foo() {
+    // Not all operating systems can name threads, so only test on those that can
+    if (Foo.namedThread()) {
+      String threadName = Thread.currentThread().getName();
+      if (!threadName.equals("MyThreadName"))
+        throw new RuntimeException("Unexpected thread name: " + threadName);
+    }
     setVal(getVal() - 1);
   }
 }