[XRay] convert FDR arg1 log entries

Summary:
A new FDR metadata record will support logging a function call argument;
appending multiple metadata records will represent a sequence of arguments
meaning that "holes" are not representable by the buffer format.  Each
call argument is currently a 64-bit value (useful for "this" pointers and
synchronization objects).

If present, we put this argument to the function call "entry" record it
belongs to, and alter its type to notify the user of its presence.

Reviewers: dberris

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D32840

llvm-svn: 314269