build: depend on a rapidjson rock that is not tied to the build host CPU

[nic-6443]

Description

lua-rapidjson compiles with -march=native, so rapidjson.so inherits the CPU features of whatever machine built it and dies with SIGILL on a machine that lacks them. ci/install-lua-rapidjson.sh worked around this by patching the flag out before building, but it only protects the paths that remember to call it — make deps and the luarocks CI runner do; the deb/rpm packages, the Docker images and a plain luarocks install apisix do not.

That is how #13736 happens. The rapidjson.so shipped in apache/apisix:3.17.0-ubuntu contains AVX-512 instructions (29 kmov* mask-register instructions), while the one in 3.17.0-debian stops at AVX2 — the packages are built per distribution, so each inherits the CPU of a different runner. Neither GCP E2 nor T2D exposes AVX-512, so on the reporter's machines the module dies as soon as its code runs. core.json.encode_stable requires rapidjson lazily on first use, which is why the crash needs a reachable upstream and does not depend on TLS: an unreachable endpoint fails before any body is encoded. 3.17.0 is the first release carrying this dependency.

This switches the dependency to api7-lua-rapidjson 0.7.2-0, which is the same 0.7.2 source with -march=native moved behind an off-by-default option (api7/lua-rapidjson#2). Every install path now gets a portable module through ordinary dependency resolution, so the patch script and its call sites are removed.

The module name is unchanged, so require("rapidjson") keeps working; cmake and a C++ compiler are still build requirements.

No new test accompanies this: the portability check lives in api7/lua-rapidjson's CI, which asserts the compile flags stay on the x86-64 baseline and scans the built module for instructions above it before a rock is published. A SIGILL on a CPU without AVX cannot be reproduced on a GitHub runner, and runtime behaviour of the swapped dependency is already covered by the existing ai-transport-http and ai-cache cases.

Which issue(s) this PR fixes

Fixes #13736

Checklist

• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible

[Copilot]

Pull request overview

This PR updates APISIX’s LuaRocks dependency on rapidjson to a portable build that is not compiled with -march=native, preventing rapidjson.so from inheriting build-host CPU features and crashing with SIGILL on older/baseline CPU models.

Changes:

• Switches the rockspec dependency from rapidjson to api7-lua-rapidjson (portable build of the same upstream source).
• Removes the ci/install-lua-rapidjson.sh workaround and deletes the script.
• Simplifies make deps and the LuaRocks CI runner by relying on normal dependency resolution.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
Makefile	Removes the explicit rapidjson patch/install step so make deps relies on rockspec dependency resolution.
ci/linux_apisix_current_luarocks_runner.sh	Drops the workaround script invocation so CI matches real-world luarocks install/make behavior.
ci/install-lua-rapidjson.sh	Deleted; workaround is no longer needed with the new dependency.
apisix-master-0.rockspec	Updates dependency to api7-lua-rapidjson = 0.7.2-0 to ensure portable builds across install paths.

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[membphis]

LGTM