Simplify dump_context by adding a dump_loc member function

Simplify dump_context by adding a dump_loc member function

This patch removes some duplicated code in dumpfile.c by
reimplementing the various dump_foo_loc calls in terms of dump_foo.

gcc/ChangeLog:
	* dump-context.h (dump_context::dump_loc): New decl.
	* dumpfile.c (dump_context::dump_loc): New member function.
	(dump_context::dump_gimple_stmt_loc): Reimplement using dump_loc
	and dump_gimple_stmt.
	(dump_context::dump_gimple_expr_loc): Likewise, using
	dump_gimple_expr.
	(dump_context::dump_generic_expr_loc): Likewise, using
	dump_generic_expr.
	(dump_context::dump_printf_loc_va): Likewise, using
	dump_printf_va.
	(dump_context::begin_scope): Explicitly using the global function
	"dump_loc", rather than the member function.

From-SVN: r263167