Remove unneeded moves in x86_64 trigger
Remove unneeded moves in x86_64 trigger

This mirrors the previous patch for x86_32: by explicitly allocating
the parameters in the registers needed for the calling sequence (and
which will be clobbered anyway), register pressure is reduced and some
move instructions can be omitted.

brandenburg/feather-trace,brandenburg/feather-trace,brandenburg/feather-trace