Fix signedness error in
9f225e992 for gcc
The first argument of vshrq_n_s8 needs to be a signed vector type,
but it was passed unsigned. Clang is more lax with conversion, but
gcc needs a cast.
Fix by me, tested by Masahiko Sawada
Per buildfarm members splitfin, batta, widowbird, snakefly, parula,
massasauga
Discussion: https://postgr.es/m/
20240306074106.mg6w4koohdlworbs%40alap3.anarazel.de