tests: Avoid variable named the same as a macro
tests: Avoid variable named the same as a macro

* tests/run-threaded.c (decrypt, verify): Don't use a variable name
that is also a macro.

--
It just looks confusing and strange at first glance.

gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme