One downside to having the changes directly in c-exp.y is that I don't 
know of any good way to conditionalize them; though I am by no means a 
bison guru.

The following diffs are unrelated to Objective-C; I'm attaching them 
just for your reference (the ones in generic.diffs are likely to be 
removed in our sources soon as well; the ones in number-parsing.diffs 
remove a memory leak caused by calling parse_number on invalid, but are 
unrelated to the Objective-C changes).