Save entire register set for dyninst runtime on aarch64 and ppclle

Save entire register set for dyninst runtime on aarch64 and ppclle

Dyninst generated calls only allow register parms, so save register set in
chunks via successive calls to enter_dyninst_uprobe_regs:
arg1 = probe index arg2 = first regno in registers arg3... registers

* runtime/dyninst/uprobes-regs.c (enter_dyninst_uprobe_regs):  New
* stapdyn/mutatee.cxx (get_dwarf_registers):  Add aarch sp.  Don't prune
   ppcle and aarch64 register set.
  (mutatee::instrument_dynprobe_target):  Add dyninst snippet to generate
   calls to enter_dyninst_uprobe_regs