Emit DWARF line entries for all data in the instruction stream.

r182712 attempted to do this, but it failed to handle data emitted via
EmitBytes.
Emit prefix data after debug and EH directives.

This ensures that the prefix data is treated as part of the function for
the purpose of debug info.  This provides a better debugging experience,
among other things by allowing a debug info client to correctly look up
a function in debug info given a function pointer.