Revert "[clang-format] Avoid inserting space after C++ casts."

This reverts commit e0219872.

This commit provokes failures in formatting tests of polly.
Cf. https://lab.llvm.org/buildbot/#/builders/205/builds/3320.

That's probably because of `)` being annotated as `CastRParen` instead of `Unknown` before, hence being kept on the same line with the next token.