libgccjit: handle long literals in playback::context::new_string_literal

libgccjit: handle long literals in playback::context::new_string_literal

gcc/jit/ChangeLog
2020-03-23  Andrea Corallo  <andrea.corallo@arm.com>

	* jit-playback.h
	(gcc::jit::playback::context m_recording_ctxt): Remove
	m_char_array_type_node field.
	* jit-playback.c
	(playback::context::context) Remove m_char_array_type_node from member
	initializer list.
	(playback::context::new_string_literal) Fix logic to handle string
	length > 200.

gcc/testsuite/ChangeLog
2020-03-23  Andrea Corallo  <andrea.corallo@arm.com>

	* jit.dg/all-non-failing-tests.h: Add test-long-string-literal.c.
	* jit.dg/test-long-string-literal.c: New testcase.