Added in flag to ask context to wait for debugger attach.

Adds in flag CREATE_FLAG_WAIT_FOR_ATTACH with value 0x0008 to the RenderScript API
to be passed down to the C++ implementation to tell it to wait for a debugger to be
attached before executing the kernel.

Change-Id: Ibc4e903efbed1b1fb14cf378d1a8517d5c8d1f26
Signed-off-by: Stephen McGroarty <stephen@codeplay.com>