libgccjit: Implement sizeof operator

gcc/jit/ChangeLog:

	* docs/topics/compatibility.rst (LIBGCCJIT_ABI_27): New ABI tag.
	* docs/topics/expressions.rst: Document gcc_jit_context_new_sizeof.
	* jit-playback.cc (new_sizeof): New method.
	* jit-playback.h (new_sizeof): New method.
	* jit-recording.cc (recording::context::new_sizeof,
	recording::memento_of_sizeof::replay_into,
	recording::memento_of_sizeof::make_debug_string,
	recording::memento_of_sizeof::write_reproducer): New methods.
	* jit-recording.h (class memento_of_sizeof): New class.
	* libgccjit.cc (gcc_jit_context_new_sizeof): New function.
	* libgccjit.h (gcc_jit_context_new_sizeof): New function.
	* libgccjit.map: New function.

gcc/testsuite/ChangeLog:

	* jit.dg/all-non-failing-tests.h: New test.
	* jit.dg/test-sizeof.c: New test.