[RenderScript] Unhide new Allocation APIs

Bug: 23535524

  - ByteBuffer getByteBuffer()
  - long getStride()
  - Allocation[] createAllocations(rs, type, usage, num)
  - long getTimeStamp()

Change-Id: I0cad88c81f9f48c7aca59af159c49f506b234aee

rs/java/android/renderscript/Allocation.java

@@ -2074,7 +2074,6 @@ public class Allocation extends BaseObj {
     }
 
     /**
-     * @hide
      * Gets or creates a ByteBuffer that contains the raw data of the current Allocation.
      * If the Allocation is created with USAGE_IO_INPUT, the returned ByteBuffer
      * would contain the up-to-date data as READ ONLY.
@@ -2109,7 +2108,6 @@ public class Allocation extends BaseObj {
     }
 
     /**
-     * @hide
      * Creates a new Allocation Array with the given {@link
      * android.renderscript.Type}, and usage flags.
      * Note: If the input allocation is of usage: USAGE_IO_INPUT,
@@ -2211,7 +2209,6 @@ public class Allocation extends BaseObj {
     }
 
     /**
-     * @hide
      * Gets the stride of the Allocation.
      * For a 2D or 3D Allocation, the raw data maybe padded so that each row of
      * the Allocation has certain alignment. The size of each row including such
@@ -2229,7 +2226,6 @@ public class Allocation extends BaseObj {
     }
 
     /**
-     * @hide
      * Get the timestamp for the most recent buffer held by this Allocation.
      * The timestamp is guaranteed to be unique and monotonically increasing.
      * Default value: -1. The timestamp will be updated after each {@link