tests/scanner/regress.c: Avoid designated initializers

Hi,

I am wondering about the status/requirements of C99 support for G-I, since this is the only part that we are using designated initializers here (and the only part that breaks pre-2013 Visual Studio builds)...

From the commit message:

As the rest of the G-I code is not using C99 syntax, let's ensure that the tests do not inadvertedly do so.

(I understand that we want to me more clear about the fields that we want to initialize in regress.c, so use a comma that follows the first field of the struct that we initialize)

With blessings, thank you!