bug in resbin.c

[Eric Burley]

there's a bug in the way that resbin.c parses version resources.  if a
string attribute of a version resource has no value, the errormessage from
line 1145 is printed:
"unexpected version string length %d != %d + %d".  This is because in this
case, the call to get_unicode for the value read the length of the next
attribute.  a check should be made before the value is read to make sure
that it's even there.  I'm working on debugging this, but I thought that
someone with more experience might have more insights.