Update Android port

* java/debug.sh (is_root): Go back to using unix sockets; allow
adb to forward them correctly.
* java/org/gnu/emacs/EmacsInputConnection.java
(getExtractedText): Don't print text if NULL.
* java/org/gnu/emacs/EmacsService.java (EmacsService): New field
`imSyncInProgress'.
(updateIC): If an IM sync might be in progress, avoid deadlocks.
* java/org/gnu/emacs/EmacsView.java (onCreateInputConnection):
Set `imSyncInProgress' across synchronization point.
* src/android.c (android_check_query): Use __atomic_store_n.
(android_answer_query): New function.
(android_begin_query): Set `android_servicing_query' to 2.
Check once, and don't spin waiting for query to complete.
(android_end_query): Use __atomic_store_n.
(android_run_in_emacs_thread): Compare-and-exchange flag.  If
originally 1, fail.
* src/textconv.c (really_set_composing_text): Clear conversion
region if text is empty.

java/org/gnu/emacs/EmacsInputConnection.java

@@ -286,6 +286,14 @@ public final class EmacsInputConnection extends BaseInputConnection
       text = EmacsNative.getExtractedText (windowHandle, request,
 					   flags);
 
+    if (text == null)
+      {
+	if (EmacsService.DEBUG_IC)
+	  Log.d (TAG, "getExtractedText: text is NULL");
+
+	return null;
+      }
+
     if (EmacsService.DEBUG_IC)
       Log.d (TAG, "getExtractedText: " + text.text + " @"
 	     + text.startOffset + ":" + text.selectionStart