use ashmem ipc in native.

this plan will be used to transcate large buffer data between two proceess.

process A:

1.ashmeme_create_region

2.mmap

3.read or write share memory.

4.close.

process B:

1.transacte fd between two process by binder's ParcelFileDescriptor.

because struct file is global for linux kernal. so binder driver can get file by fget, and map file to anthoer process with new fd. API target_fd_install.

2.mmap

3.read or write share memory

4.close