Shift 1U instead, to make sure it's unsigned; the result of, for
example, the result of shifting a signed value left is undefined if the
value times 2^{shift count} doesn't fit in the *signed* type of the
shifted value. That means, in particular, that the result of shifting 1
left by {number of bits in an int - 1} is undefined. (In *practice*,
it'll probably be -2^32, with the bit you want set, but that's not
guaranteed, and GCC 5.1 seems not to like it.)
Make some other left-hand operands of <<, and some variables holding
results from shifts of that sort, unsigned, while we're at it.
Change-Id: Ie72a9d0d518f59b35948267d10c80735d162e8bb
Reviewed-on: https://code.wireshark.org/review/8264
Reviewed-by: Guy Harris <guy@alum.mit.edu>