AArch64: Use long for pointers in RS Java/JNI code

Changes include
[x] Some JNI functions, with return type jlong, casts
    pointer to jint before returning it. This has been fixed.

[x] Minor JNI function prototype changes where
    formal paramter type has been changed to a JNI
    type (int to jint for example).

[x] long is used for ScriptC, Sampler, Font, ProgramStore
    handles as they can be 64-bit.

[x] A new hidden constructor ScriptC(long, RenderScript)
    has been added. This should eventually replace public
    API method ScriptC(int, RenderScript).

[x] Font and FileA3D use getNativeAsset instead of getAssetInt
    to get Asset Handles. The getAssetInt method will be
    deprecated in favor of getNativeAsset, as the former does
    not support 64-bit.

[x] rsnPathCreate method accepts loop as an int. This should
    be long as the underlying RS function assumes this to be
    a pointer.

Change-Id: I919d857e5933febe63966049da83de9f9adee6f5
Signed-off-by: Ashok Bhat <ashok.bhat@arm.com>