More RS exceptions cleanup.
Remove some dead code.

Change-Id: If97e3fdfe6de7bb28f22e1c5ee748c81cea3db93
diff --git a/graphics/java/android/renderscript/RenderScript.java b/graphics/java/android/renderscript/RenderScript.java
index 8f1f273..21efa39 100644
--- a/graphics/java/android/renderscript/RenderScript.java
+++ b/graphics/java/android/renderscript/RenderScript.java
@@ -156,10 +156,6 @@
     synchronized void nObjDestroy(int id) {
         rsnObjDestroy(mContext, id);
     }
-    native int  rsnFileOpen(int con, byte[] name);
-    synchronized int nFileOpen(byte[] name) {
-        return rsnFileOpen(mContext, name);
-    }
 
     native int  rsnElementCreate(int con, int type, int kind, boolean norm, int vecSize);
     synchronized int nElementCreate(int type, int kind, boolean norm, int vecSize) {
@@ -599,7 +595,7 @@
 
     void validate() {
         if (mContext == 0) {
-            throw new IllegalStateException("Calling RS with no Context active.");
+            throw new RSInvalidStateException("Calling RS with no Context active.");
         }
     }