MFC r255777: Omit "__restrict" when generating syscall argument strings

syscall argument strings are also regenerated as part of this commit
MFC r257143: Fix a couple of bugs in the fasttrap emulation of a "push
%rbp" instruction
MFC r254266,254309: Add event handlers for module load and unload events

This is just a merge of EVENTHANDLER.9, the actual code chnage was merged earlier.