Partially support streaming of poly_int for offloading.

When offloading is enabled, the patch streams out host
NUM_POLY_INT_COEFFS, and changes streaming in as follows:

if (host_num_poly_int_coeffs <= NUM_POLY_INT_COEFFS)
{
  for (i = 0; i < host_num_poly_int_coeffs; i++)
    poly_int.coeffs[i] = stream_in coeff;
  for (; i < NUM_POLY_INT_COEFFS; i++)
    poly_int.coeffs[i] = 0;
}
else
{
  for (i = 0; i < NUM_POLY_INT_COEFFS; i++)
    poly_int.coeffs[i] = stream_in coeff;

  /* Ensure that degree of poly_int <= accel NUM_POLY_INT_COEFFS.  */
  for (; i < host_num_poly_int_coeffs; i++)
    {
      val = stream_in coeff;
      if (val != 0)
	error ();
    }
}

gcc/ChangeLog:
	PR ipa/96265
	PR ipa/111937
	* data-streamer-in.cc (streamer_read_poly_uint64): Remove code for
	streaming, and call poly_int_read_common instead.
	(streamer_read_poly_int64): Likewise.
	* data-streamer.cc (host_num_poly_int_coeffs): Conditionally define
	new variable if ACCEL_COMPILER is defined.
	* data-streamer.h (host_num_poly_int_coeffs): Declare.
	(poly_int_read_common): New function template.
	(bp_unpack_poly_value): Remove code for streaming and call
	poly_int_read_common instead.
	* lto-streamer-in.cc (lto_input_mode_table): Stream-in host
	NUM_POLY_INT_COEFFS into host_num_poly_int_coeffs if ACCEL_COMPILER
	is defined.
	* lto-streamer-out.cc (lto_write_mode_table): Stream out
	NUM_POLY_INT_COEFFS if offloading is enabled.
	* poly-int.h (MAX_NUM_POLY_INT_COEFFS_BITS): New macro.
	* tree-streamer-in.cc (lto_input_ts_poly_tree_pointers): Adjust
	streaming-in of poly_int.

Signed-off-by: Prathamesh Kulkarni <prathameshk@nvidia.com>