Add PACKAGE="<package name>" to .Call()

[billdenney]

I have an issue with the systemfonts package that appears likely to do with the order that packages are loaded (though I'm not certain). It is fixed by adding PACKAGE="systemfonts" to the .Call() function call (r-lib/systemfonts#53 (comment)).

At least in this scenario, it would be helpful if at the end of every .Call() the PACKAGE="<package name>" were added. I'm not familiar enough with .Call() to know if that would ever be a bad idea.

[jimhester]

We actually had included this feature previously, but was inadvertently disabled in a refactoring.

[billdenney]

Thanks!