[XRay][tools] Support arg1 logging entries in the basic logging mode

[XRay][tools] Support arg1 logging entries in the basic logging mode

Summary:
The arg1 logging handler changed in compiler-rt to start writing a
different type for entries encountered when logging the first argument
of XRay-instrumented functions. This change allows the trace loader to
support reading these record types as well as prepare for when the
basic (naive) mode implementation starts writing down the argument
payloads.

Without this change, binaries with arg1 logging support enabled start
writing unreadable logs for any of the XRay tracing tools.

Reviewers: pelikan

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D38550

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314967 91177308-0d34-0410-b5e6-96231b3b80d8