gccrs: libproc_macro: Add cpp Span representation

Add Span representation in libproc_macro cpp part of the library.
Integrate spans to existing types.

gcc/rust/ChangeLog:

	* util/rust-token-converter.cc (convert): Update call to
	constructors with location information.
	(handle_suffix): Convert token locus to a Span and use it in the
	literal.

libgrust/ChangeLog:

	* libproc_macro/Makefile.am: Add span.cc
	* libproc_macro/Makefile.in: Regenerate.
	* libproc_macro/span.cc: New file.
	* libproc_macro/span.h: New file.
	* libproc_macro/group.cc (Group::make_group): Add span
	argument.
	* libproc_macro/group.h (GROUP_H): Add include
	directive for spans.
	* libproc_macro/ident.cc (Ident__new): Add span
	argument.
	(Ident__new_raw): Likewise.
	(Ident::make_ident): Likewise.
	* libproc_macro/ident.h (Ident__new): Likewise.
	(Ident__new_raw): Likewise.
	* libproc_macro/literal.cc (Literal::clone): Clone the
	span.
	(Literal::make_literal): Add span argument.
	(Literal::make_u8): Likewise.
	(Literal::make_u16): Likewise.
	(Literal::make_u32): Likewise.
	(Literal::make_u64): Likewise.
	(Literal::make_i8): Likewise.
	(Literal::make_i16): Likewise.
	(Literal::make_i32): Likewise.
	(Literal::make_i64): Likewise.
	(Literal::make_string): Likewise.
	(Literal::make_byte_string): Likewise.
	(Literal::make_f32): Likewise.
	(Literal::make_f64): Likewise.
	(Literal::make_char): Likewise.
	(Literal::make_usize): Likewise.
	(Literal::make_isize): Likewise.
	* libproc_macro/literal.h (struct Literal): Add span to
	Literal structure.
	* libproc_macro/punct.cc (Punct::make_punct): Add span
	argument to punct constructor.
	* libproc_macro/punct.h (struct Punct): Add span to
	Punct structure.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>