s4-samdb: internal s4 ldb modules should be GPL not LGPL

s4-samdb: internal s4 ldb modules should be GPL not LGPL

I think these modules ended up LGPL because someone based the module
on an existing LGPL module in the core ldb, and it spread from
there. Certainly there is no reason for the ldb modules that are not
distributed as part of ldb to be LGPL.