Undefined left shift by -1 in ord2w_dloghyb

[jschanck]

It is possible for the following line to be executed with ord=1, in which case the left shift is undefined.

PQCrypto-SIDH/src/compression/dlog.c

Line 183 in 0b6f740

if (i_j >= (1 << (ord-2))) {

It would be OK to multiply through by 2 or 4 here, there's no risk of overflow.

[patricklonga]

Thanks for reporting this issue, John. A related variable wasn't properly corrected to the range [0, p-1] before being tested against 0. I pushed a fix.