Prefer explicit construction to coercion in record initialization

While we support initializing records via coercion from an expression
list, e.g.,

    local x: X = [$x1=1, $x2=2];

this can sometimes obscure the code to readers, e.g., when assigning to
value declared and typed elsewhere. The language runtime has a similar
overhead since instead of just constructing a known type it needs to
check at runtime that the coercion from the expression list is valid;
this can be slower than just writing the readible code in the first
place, see #4559.

With this patch we use explicit construction, e.g.,

    local x = X($x1=1, $x2=2);

scripts/policy/protocols/ftp/software.zeek

@@ -23,6 +23,6 @@ event ftp_request(c: connection, command: string, arg: string) &priority=4
 	{
 	if ( command == "CLNT" )
 		{
-		Software::found(c$id, [$unparsed_version=arg, $host=c$id$orig_h, $software_type=CLIENT]);
+		Software::found(c$id, Software::Info($unparsed_version=arg, $host=c$id$orig_h, $software_type=CLIENT));
 		}
 	}