Fixed "This function declaration is not a prototype" errors in Xcode 9

[sgravrock]

Cedar's headers declare no-args functions in a way that means "this function takes no arguments" in C++ but "this function takes an unspecified number of arguments" in C and Objective-C. With the default project settings applied, Xcode treats those declarations as errors.

[tjarratt]

Woah, rad. Thanks for the PR Steven !

I’ll take some time to merge this PR tonight but it looks eminently mergeable.

Out of curiosity, did you look at the test failure ? Is it unrelated or did this manage to break anything in our test suite ?

[sgravrock]

It looks unrelated to me:

==> xcodebuild -project Cedar.xcodeproj -configuration Release clean analyze ARCHS=i386 -target "Cedar-iOS StaticLib Specs" -sdk "iphonesimulator8.1" SYMROOT='/Users/travis/build/cedarbdd/cedar/build'
xcodebuild: error: SDK "iphonesimulator8.1" cannot be located.

Locally, I get hundreds of lines of error output from com.apple.CoreSimulator, most of them relating to services crashing and being restarted. That happens both before and after my change. I'm not sure if something's wrong with my environment or if ios-sim has gone the way of the tools it replaced.