QUIC: unroll and inline ngx_quic_varint_len()/ngx_quic_build_int(). According to profiling, those two are among most frequently called, so inlining is generally useful, and unrolling should help with it. Further, this fixes undefined behaviour seen with invalid values. Inspired by Yu Liu.

if exists("b:did_indent")
    finish
endif
let b:did_indent = 1

setlocal indentexpr=

" cindent actually works for nginx' simple file structure
setlocal cindent
" Just make sure that the comments are not reset as defs would be.
setlocal cinkeys-=0#