UXP/db/sqlite3

This is the SQLite amalgamation.
Check sqlite3.h for the version number and source id.

See http://www.sqlite.org/ for more info.

We have a UXP-specific moz.build in src/ (normally not there) that we
use to build. Adfditionally, src/ contains sqlite.symbols which lists
all explicitly exported symbols from the library to expose.

To move to a new version:

Copy the sqlite3.h and sqlite3.c files from the amalgamation of sqlite.

Be sure to update SQLITE_VERSION accordingly in $(topsrcdir)/old-configure.in.