C99 support

[ChrisJefferson]

Ward does not support C99-style variable declarations (the Int i = 0 at the start of the for loop)

for (Int i = 0; i < HookCount; ++i) {
     struct InterpreterHooks * hook = activeHooks[i];
    if (hook && hook->visitStat) { (hook->visitStat)(stat); } 
};

[rbehrends]

A related C99 issue is the support for variable declarations that occur in the middle of a statement block and that also need to be handled properly.