Fix issue #215 (internal compiler error)

Visual Studio 2017 produces an internal compiler error in _release_ mode for the function call _mm512_broadcast_i32x4(_mm_set_epi64x(a, b)). Affected are the AEGIS algorithms aegis-128x4 and aegis-256x4.

The AVX512 instruction _mm512_broadcast_i32x4 is replaced by simpler, but otherwise equivalent instructions, which do not confuse the VS2017 optimizer.