compile_commands.json (a.k.a. "compdb", https://clang.llvm.org/docs/JSONCompilationDatabase.html) is intended to help stand-alone C-family LSP servers index the codebase as precisely as possible. The actively maintained LSP servers with good C++ support are: - Clangd (https://clangd.llvm.org/) - CCLS (https://github.com/MaskRay/ccls) This change causes a successful invocation of configure.py to create a unified Scylla+Seastar+Abseil compdb for every selected build mode, and to leave a valid symlink in the source root (if a valid symlink already exists, it will be left alone). Signed-off-by: Michael Livshin <michael.livshin@scylladb.com> Closes #9558