build-sys: Move svolume-*.c to libpulsecore

The various software volume implementations were being built as part of
libpulsecommon for some reason. These should only ever be used in the
daemon, so they should be in libpulsecore.
2 jobs for master in 6 minutes and 4 seconds (queued for 3 minutes and 36 seconds)
Status Job ID Name Coverage
  Build
passed #475004
build-autotools

00:04:52

passed #475005
build-meson

00:01:11