Convert vrange dumping facilities to pretty_printer.

Convert vrange dumping facilities to pretty_printer.

We need to dump global ranges from the gimple pretty printer code, but
all the vrange dumping facilities work with FILE handles.  This patch
converts all the dumping methods to work with pretty printers, and
provides a wrapper so the FILE * methods continue to work for
debugging.  I also cleaned up the code a bit.

Tested on x86-64 Linux.

gcc/ChangeLog:

	* Makefile.in (OBJS): Add value-range-pretty-print.o.
	* pretty-print.h (pp_vrange): New.
	* value-range.cc (vrange::dump): Call pp version.
	(unsupported_range::dump): Move to its own file.
	(dump_bound_with_infinite_markers): Same.
	(irange::dump): Same.
	(irange::dump_bitmasks): Same.
	(vrange::debug): Remove.
	* value-range.h: Remove virtual designation for dump methods.
	Remove dump_bitmasks method.
	* value-range-pretty-print.cc: New file.
	* value-range-pretty-print.h: New file.