Thread language through c_type_print_args

Thread language through c_type_print_args

Currently dwarf2read.c will pass the CU's language to
c_type_print_args -- but this doesn't affect all aspects of type
printing, because some code in c-typeprint.c refers to
current_language.

This patch threads the language through more of the type printing
code, adding an overload to c_type_print.  Some uses of
current_language remain, but now they are only in top-level functions.

gdb/ChangeLog
2018-06-01  Tom Tromey  <tom@tromey.com>

	* dwarf2read.c (dwarf2_compute_name): Pass CU's language to
	c_print_type.
	* c-typeprint.c (c_print_type_1): Add "language" parameter.
	(c_print_type): Update.
	(c_print_type): New overload.
	(c_type_print_varspec_prefix, c_type_print_args)
	(c_type_print_varspec_suffix, c_print_type_no_offsets)
	(c_type_print_base_struct_union, c_type_print_base_1)
	(cp_type_print_method_args): Add "language" parameter.
	(c_type_print_base): Update.
	* c-lang.h (c_print_type): Add new overload.