lib/alg-gost3411-core.c: fix conversion error seen by sensitive compilers
lib/alg-gost3411-core.c: fix conversion error seen by sensitive compilers

Some compiler might be sensitive and raise an Warning/error on this line.

Signed-off-by: Guillaume W. Bres <a9e7fa3d193939da9b9ffb7532af4b97f88b2ebe@gmail.com>

besser82/libxcrypt,besser82/libxcrypt,besser82/libxcrypt,besser82/libxcrypt