Rename netutils, jconf, stream, aead, aead2022, aead2022_udp, crypto,
acl, plugin, plugin_disabled and resolv from .c to .cpp without changing
their contents, and update source lists, snippet references, test
comments and debian/copyright.
The Doxygen source list and scripts/check_cli_docs.py now accept either
extension for each module, so the remaining programs can move one at a
time. The new .cpp files are added to the no-heap ratchet baseline.
Rename base64, json, ipset, process, ppbloom, rule, ssurl and cache from
.c to .cpp without touching their contents, and update the CMake source
lists, debian/copyright and the docs.
Ported code keeps -Wall; -Wextra is now opt-in through
ss_strict_warnings() for code written as C++ (the core tests).
check_no_heap.py gains a ratchet baseline for the converted modules,
which still allocate the way the C code did. A new check_cxx_runtime
test verifies with nm that the programs and libshadowsocks-c.a still
need no C++ runtime library, so C consumers are unaffected.
Max Lv