When embedded SQLITE is used:
* HAVE_SQLITE is *not* defined
* patch it to add the PRAGMA command
* linked as static

When system SQLITE is used:
* HAVE_SQLITE is defined
* obviously not patched for PRAGMA
* linked as dynamic => override the sqlite3CreateFunc function
* For WIN32 (or MacOSX) we would need to use another mechanism (see lattice.umiacs.umd.edu/files/functions_tr.pdf) => impose embedded static lib

Possible solutions in the future:
1 - make SQLite implement the required PRAGMA (patch proposed)
2 - don't use the required PRAGMA at all, and manage to intercept the sqlite3CreateFunc call
    when statically linked (=> modify the source code of SQLite) 
