Use bound_minimal_symbol in var_msym_value_operation

Use bound_minimal_symbol in var_msym_value_operation

This changes var_msym_value_operation to use a bound_minimal_symbol
rather than separate minsym and objfile parameters.  The main benefit
of this is removing the possibly-confusing check_objfile overload for
a plain minimal symbol.

gdb/ChangeLog
2021-03-08  Tom Tromey  <tom@tromey.com>

	* parse.c (parser_state::push_symbol, parser_state::push_dollar):
	Update.
	* p-exp.y (variable): Update.
	* go-exp.y (variable): Update.
	* expprint.c (dump_for_expression): Use bound_minimal_symbol.
	Remove overload for objfile.
	* expop.h (eval_op_var_msym_value): Use bound_minimal_symbol
	parameter.
	(check_objfile): Likewise.
	(dump_for_expression): Likewise.  Remove overload for objfile.
	(class var_msym_value_operation): Use bound_minimal_symbol.
	* eval.c (eval_op_var_msym_value): Use bound_minimal_symbol
	parameter.
	(var_msym_value_operation::evaluate_for_address)
	(var_msym_value_operation::evaluate_for_sizeof)
	(var_msym_value_operation::evaluate_for_cast): Update.
	* d-exp.y (PrimaryExpression): Update.
	* c-exp.y (variable): Update.
	* ax-gdb.c (var_msym_value_operation::do_generate_ax): Update.
	* ada-lang.c (ada_var_msym_value_operation::evaluate_for_cast):
	Update.
	* ada-exp.y (write_var_or_type): Update.