Bounds on variables may use undefined values

[kyleheadley]

similar to #524, but outside of function prototypes

3C will infer : count(length) bounds on arrays from related variables, but those variables may not be in the local scope. for example, from icecast:

connection.c:456:44: error: use of undeclared identifier 'dst'
    _Array_ptr<struct pollfd> ufds : count(dst);
                                           ^

and the pre-converted code is:

    struct pollfd ufds [global.server_sockets];
    if(...) {
        ...
    else {
        int dst;
        ...
        global.server_sockets = dst;
        ...
    }

from yacr2:

./channel.h:42:38: error: use of undeclared identifier 'channelColumns'
extern _Array_ptr<ulong> TOP : count(channelColumns);
                                     ^

This file contains global defs and channelColumns is defined soon after TOP (along with other counters). I assume the connection is made from usage in another file.