Fix uninitialized read error reported by MSAN.

The problem was that our Obj -> Yaml dumper had not been taught
to handle certain types of records.  This meant that when I
generated the test input files, the records were still there but
none of its fields were filled out.  So when it did the
Yaml -> Obj conversion as part of the test, it generated records
with garbage in them.

The patch here fixes the Obj <-> Yaml converter, and additionally
updates the test file with fresh Yaml generated by the fixed
converter.

llvm-svn: 322029