gdb: fix invalid arg coercion when calling static member functions

gdb: fix invalid arg coercion when calling static member functions

In this commit:

  commit 7022349d5c86bae74b49225515f42d2e221bd368
  Date:   Mon Sep 4 20:21:13 2017 +0100

      Stop assuming no-debug-info functions return int

A new if case was added to call_function_by_hand_dummy to decide if a
function should be considered prototyped or not.  Previously the code
was structured like this:

  if (COND_1)
    ACTION_1
  else if (COND_2)
    ACTION_2
  else
    ACTION_3

With the new block the code now looks like this:

  if (COND_1)
    ACTION_1
  if (NEW_COND)
    NEW_ACTION
  else if (COND_2)
    ACTION_2
  else
    ACTION_3

Notice the new block was added as and 'if' not 'else if'.  I'm running
into a case where GDB executes ACTION_1 and then ACTION_2.  Prior to
the above commit GDB would only have executed ACTION_1.

The actions in the code in question are trying to figure out if a
function should be considered prototyped or not.  When a function is
not prototyped some arguments will be coerced, e.g. floats to doubles.

The COND_1 / ACTION_1 are a very broad, any member function should be
considered prototyped, however, after the above patch GDB is now
executing the later ACTION_2 which checks to see if the function's
type has the 'prototyped' flag set - this is not the case for the
member functions I'm testing, and so GDB treats the function as
unprototyped and casts the float argument to a double.

I believe that adding the new check as 'if' rather than 'else if' was
a mistake, and so in this commit I add in the missing 'else'.

gdb/ChangeLog:

	* infcall.c (call_function_by_hand_dummy): Add missing 'else' when
	setting prototyped flag.

gdb/testsuite/ChangeLog:

	* gdb.cp/method-call-in-c.cc (struct foo_type): Add static member
	function static_method.
	(global_var): New global.
	(main): Use new static_method to ensure it is compiled in.
	* gdb.cp/method-call-in-c.exp: Test calls to static member
	function.