fbc: PROCPTR( proc [, signature ] )

- don't allow anything but procedures throw an error otherwise
- internal: new use of cIdentifierOrUdtMember() may return a variable type
  since it is less restrictive than the previous use of cIdentifier()

Example:
	type T extends object
		as integer n
		declare sub proc()
	end type

	var p1 = procptr( T.proc )  '' OK
	var p2 = procptr( T.n )     '' error: illegal non-static member access
	dim as T a
	var p3 = procptr( a.proc )  '' error: invalid data types before '.'

src/compiler/parser-expr-unary.bas

@@ -686,6 +686,15 @@ function cAddrOfExpression( ) as ASTNODE ptr
 			return astNewCONSTi( 0 )
 		end if
 
+		select case symbGetClass( sym )
+		case FB_SYMBCLASS_PROC
+		case else
+			errReport( FB_ERRMSG_INVALIDDATATYPES, TRUE )
+			'' error recovery: skip until ')' and fake a node
+			hSkipUntil( CHAR_RPRNT, TRUE )
+			return astNewCONSTi( 0 )
+		end select
+
 		hCheckEmptyProcParens()
 
 		'' ',' ?