Clean up arguments to evaluate_subexp_do_call

Clean up arguments to evaluate_subexp_do_call

I noticed hat evaluate_subexp_do_call takes an array of arguments and
a count -- but, unlike the usual convention, the count does not
include the first element.

This patch changes this function to match call_function_by_hand --
passing the callee separately, and using an array_view for the
arguments.  This makes it simpler to understand.

Regression tested on x86-64 Fedora 28.

gdb/ChangeLog
2020-12-15  Tom Tromey  <tom@tromey.com>

	* f-lang.c (evaluate_subexp_f): Update.
	* expression.h (evaluate_subexp_do_call): Update.
	* eval.c (evaluate_subexp_do_call): Add callee parameter.  Replace
	nargs, argvec with array_view.
	(evaluate_funcall): Update.