xtensa: fix ICE on pr59037.c test

xtensa: fix ICE on pr59037.c test

xtensa gcc gets ICE on pr59037.c test because its xtensa_output_literal
function cannot handle integer literals of sizes other than 4 and 8,
whereas the test uses 16-byte int vector.
Split integer literal formatting into the recursive function
xtensa_output_integer_literal_parts capable of handling literals of any
power of 2 size not less than 4.

2016-11-02  Max Filippov  <jcmvbkbc@gmail.com>
gcc/
	* config/xtensa/xtensa.c (xtensa_output_integer_literal_parts):
	New function.
	(xtensa_output_literal): Use xtensa_output_integer_literal_parts
	to format MODE_INT and MODE_PARTIAL_INT literals.

From-SVN: r241800