This patch doesn't really tests whether osmo-pcu can work on a multi-bts
environment, but it prepares the data structures to be able to do so at
any later point in time.
Change-Id: I6b10913f46c19d438c4e250a436a7446694b725a
In Release 5, Fixed Allocations were removed as part of a "GPRS
simplification project" inside 3PGPP. This means that any MS compatible
with Rel-5 or higher may not support it, which makes implementation
in the PCU af historical interest only. See Tdoc GP-021277 for the
actual removal, it happened at 5.0.0 time.
Change-Id: I8138bc0a47d3468b67cec866447fd4b0fc69d4c5