[clang-format] Restrict the special handling for K&R C to C/C++

Commits 58494c85, f6bc6145, and 0fc27ef1 added special
handlings for K&R C function definitions and caused some
JavaScript/TypeScript regressions which were addressed in D107267,
D108538, and D108620. This patch would have prevented these known
regressions and will fix any unknown ones.

Differential Revision: https://reviews.llvm.org/D109582