UNOIDL identifiers starting with a lowercase letter and containing underscores
are reserved for the implementation.  It would be good to be able to enforce
that in code parsing UNOIDL files, but some existing identifiers violate that.
So at least change any violating method parameter identifiers here.  While that
is theoretically an incompatible change for published interfaces, it practically
does not matter at all.

Change-Id: I5eff17b5dd5e2e92984184127c4fe1712d62c9dd