ci(codeql): manual c-cpp build replaces autobuild

[CryptoJones]

CodeQL's autobuilder has been failing on every PR (including doc-only ones — see #44, #47, #48) with:

cpp/autobuilder: Incompatible operating system (expected Windows).
cpp/autobuilder: No supported build system detected.

The autobuilder scans the repo root for a recognized build file (Makefile, CMakeLists.txt, etc.); the decompiler's Makefile lives at Ghidra/Features/Decompiler/src/decompile/cpp/, so the scan fails and the c-cpp matrix leg goes red even when no C++ source is touched. The actual Java/Kotlin, Actions, and Python legs have always been fine; only c-cpp was affected.

Fix: replace the github/codeql-action/autobuild@v3 step with an explicit make libdecomp_dbg.a invocation that cds into the decompiler tree. libdecomp_dbg.a is the static-archive target that compiles every LIBDECOMP_NAMES source into com_dbg/*.o then ar qcs them; it does NOT need BFD at link time (no -lbfd dependency), so binutils-dev / libiberty-dev drop out of the apt-get list too. CodeQL's tracer picks up the .o compile commands during the make invocation, which is exactly the input static analysis needs.

The autobuild step stays for the actions and python matrix legs (it works fine for both — actions is just YAML, python doesn't need a build at all).

Proudly Made in Nebraska. Go Big Red! 🌽 https://xkcd.com/2347/

[CryptoJones]

Superseded by #74. PR #51's squash-merge accidentally included PR #50's first commit (the wrong-binutils-dev attempt), so PR #50 in current form would re-apply that already-landed commit AND the second one — hence the unresolvable conflict. PR #74 cherry-picks only the second-commit fix (binutils-dev added back) onto current master.