[APInt] Remove support for wrapping from APInt::setBits.

This features isn't used anywhere in tree. It's existence seems to be preventing selfhost builds from inlining any of the setBits methods including setLowBits, setHighBits, and setBitsFrom. This is because the code makes the method recursive.

If anyone needs this feature in the future we could consider adding a setBitsWithWrap method. This way only the calls that need it would pay for it.

llvm-svn: 301769