Speedups: remove dependency on c++ (#2796)

* Speedups: remove dependency on c++

* Speedups: intset: handle malloc failing

* Speedups: intset: fix corner case for int64 on 32bit systems

original idea was to only use bucket->val if int<pointer,
but we always have a union now anyway

* Speedups: add size comment to player_set bucket configuration

* test: more tests for LocationStore.find_item

* test: require _speedups in CI

This kind of tests that the build succeeds.

* test: even more tests for LocationStore.find_item

* Speedups: intset uniform comment style

* Speedups: intset: avoid memory leak when realloc fails

* Speedups: intset: make `gcc -pedantic -std=c99 -fanalyzer` without warnings

Unnamed unions are not in C99, this got fixed.
The overhead of setting count=0 is minimal or optimized-out and silences -fanalizer (see comment).

* Speedups: don't leak memory in case of exception

* Speedups: intset: validate alloc and free

This won't happen in our cython, but it's still a good addition.

* CI: add test framework for C/C++ code

* CI: ctest: fix cwd

* Speedups: intset: ignore msvc warning

* Tests: intset: revert attempt at no-asan

We solve this with env vars in ctest now, and this fails for msvc.

* Test: cpp: docs: fix typo

* Test: cpp: docs: fix another typo

* Test: intset: proper bucket count for Negative test

INTxx_MIN % 1 would not produce a negative number, so the test was flawed.

.github/workflows/ctest.yml

@@ -0,0 +1,54 @@
+# Run CMake / CTest C++ unit tests
+
+name: ctest
+
+on:
+  push:
+    paths:
+      - '**.cc?'
+      - '**.cpp'
+      - '**.cxx'
+      - '**.hh?'
+      - '**.hpp'
+      - '**.hxx'
+      - '**.CMakeLists'
+      - '.github/workflows/ctest.yml'
+  pull_request:
+    paths:
+      - '**.cc?'
+      - '**.cpp'
+      - '**.cxx'
+      - '**.hh?'
+      - '**.hpp'
+      - '**.hxx'
+      - '**.CMakeLists'
+      - '.github/workflows/ctest.yml'
+
+jobs:
+  ctest:
+    runs-on: ${{ matrix.os }}
+    name: Test C++ ${{ matrix.os }}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, windows-latest]
+
+    steps:
+    - uses: actions/checkout@v4
+    - uses: ilammy/msvc-dev-cmd@v1
+      if: startsWith(matrix.os,'windows')
+    - uses: Bacondish2023/setup-googletest@v1
+      with:
+        build-type: 'Release'
+    - name: Build tests
+      run: |
+        cd test/cpp
+        mkdir build
+        cmake -S . -B build/ -DCMAKE_BUILD_TYPE=Release
+        cmake --build build/ --config Release
+        ls
+    - name: Run tests
+      run: |
+        cd test/cpp
+        ctest --test-dir build/ -C Release --output-on-failure