Fix some types in mmapped_file.
Add remote_ptr.
Make mmapped_file::start/end use remote_ptr.
Rename TraceFstream to TraceStream.

It's not very much like a C++ fstream.
Remove fstream typedef.
Rename mmapped_file to TraceMappedRegion.
Move TraceMappedRegion to its own header file.
Put {} around uses of RR_ARCH_FUNCTION to help clang-format (and Eclipse) get the code formatting right.
Add constructor for TraceMappedRegion and use it.
Remove TraceMappedRegion::time; it's only used for asserts (which are not all that likely to catch hard bugs).
Remove TraceMappedRegion::tid since it's not used for anything.
Wrap TraceMappedRegion::copied in a getter.
Simplify TraceMappedRegion::size().
Wrap access to TraceMappedRegion::filename in a getter.
Wrap TraceMappedRegion::stat in a getter.
Wrap TraceMappedRegion::start/end in getters.
Make TraceMappedRegion a class with private fields.
add helper functions for multi-architecture syscall numbers
use X86Arch everywhere in is_always_emulated_syscall
add an easy way of getting arch from AutoRemoteSyscalls