The Syntax enumeration requires at least three bits to store all of its...

The Syntax enumeration requires at least three bits to store all of its values. Increase the number of bits for SyntaxUsed. Decrease the number of expression arguments allowed by a single bit so that the bit fields continue to add up to 32-bits evenly.

There is no test for this fix because I could find no reasonable way to trigger a visible failure from it.

Thanks to Doug Gregor for spotting this!

llvm-svn: 222456