Make replayer.cc build with DEBUGTAG.
Split syscall_insn definition since the syscall used by glibc might not be the one we use for remote syscalls.
Rename remote_syscalls.h/.cc to AutoRemoteSyscalls.h/.cc
Switch AutoRestoreMem::data to 'vector'.
Switch restore_scratch logic to a helper class.

Incidentally switches temp data storage from malloc to vector.
Remove filter functionality from iterate_memory_map since it's unused. Also removes memory-reading feature since it's not used.
Use variable-length array instead of malloc for temp storage.
Remove current_state_buffer and cleanup_code_injection since they're unused.
rework Registers to use more C++-y features for initialization
make Registers::total_registers() multi-architecture aware
teach preload.c to cope with differently-named syscalls for 32/64-bit
fix printf -Wformat error in preload.c
write traced syscall assembly for x86-64
make vsyscall hooking in libpreload x86-only
write cpuid_loop.S assembly for x86-64
un-#ifdef write_socketcall_args in task.cc
Split session.h/.cc into Session/ReplaySession/RecordSession.h/.cc.
Move AutoGC into EmuFs.
Remove EmuFs and EmuFile tags, since they're not really used.
Rename emufs.h/.cc to EmuFs.h/.cc.