Sources here are from luasql git tag 2.8.1
(https://github.com/lunarmodules/luasql/tree/2.8.1)
Some modifications have been done to them:
- LUASQL_VERSION_NUMBER defined in luasql.h
- Cleared trailing tabs from ls_mysql.c
  Equivalent patch submitted to upstream.
- Fixed misleading indentation in ls_sqlite3.c
- Removed unused variables from ls_odbc.c
- Cleared trailing tabs from ls_odbc.c

Only the files needed by freeciv are included here, not entire luasql
source directory hierarchy.
The ls_*.h files are our own additions to use those backends directly.
