"sqlite3.c" and "sqlite3.h" files from sqlite-amalgamation-3090200.zip (SQLite 3.9.2 2015-11-02)

Those files are provided for easy setup and compatibility under Windows/Linux/MacOS. They are used by default by the CMake build.

Use -DSQLITECPP_INTERNAL_SQLITE=OFF to link against the Linux "libsqlite3-dev" package instead.