* cmake: Enable CMAKE_EXPORT_COMPILE_COMMANDS
Enabling this option causes CMake to generate a compile_commands.json file
containing a compilation database that can be used to drive third-party tools.
CMAKE_EXPORT_COMPILE_COMMANDS only exists for CMake >= 3.5
Exporting compilation databases is only supported for Makefile and Ninja
generators, so check these conditions as well.
CMAKE_EXPORT_COMPILE_COMMANDS is only enabled in supported configurations
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