fix - function call with variadic parameter for type "any"

Hello,

Our implementation of variadic parameters are not complete. The
support of "any" type is incomplete. Modificator VARIADIC for funccall
parameters needs transformation from ArrayExpr to standard parameters
list.

==current behave==
postgres=# select variadic_demo2(10,'Petr',20,20,30);
NOTICE:  arg(0) = 10
NOTICE:  arg(1) = Petr
NOTICE:  arg(2) = 20
NOTICE:  arg(3) = 20
NOTICE:  arg(4) = 30
 variadic_demo2
----------------

(1 row)

Time: 3,245 ms
postgres=# select variadic_demo2(10,'Petr',20, variadic array[10,20]);
NOTICE:  arg(0) = 10
NOTICE:  arg(1) = Petr
NOTICE:  arg(2) = 20
NOTICE:  arg(3) = {10,20}
 variadic_demo2
----------------

(1 row)

==fixed behave==

Time: 1,287 ms
postgres=# select variadic_demo2(10,'Petr',20,20,30);
NOTICE:  arg(0) = 10
NOTICE:  arg(1) = Petr
NOTICE:  arg(2) = 20
NOTICE:  arg(3) = 20
NOTICE:  arg(4) = 30
 variadic_demo2
----------------

(1 row)

Time: 0,994 ms
postgres=# select variadic_demo2(10,'Petr',20, variadic array[10,20]);
NOTICE:  arg(0) = 10
NOTICE:  arg(1) = Petr
NOTICE:  arg(2) = 20
NOTICE:  arg(3) = 10
NOTICE:  arg(4) = 20
 variadic_demo2
----------------

(1 row)

regards
Pavel Stehule