Interestingly enough, talloc_ctx_init() actually had not a single caller.
While dropping it, see to it that the few contexts that are actually used in
osmo-bsc.git are indeed initialized in all the main scopes.
Also initialize two void* ctxts as NULL explicitly, to allocate under the NULL
context in case some main scope forgets to branch it off another root context.
(That's bsc, fle and paging, all others actually come in from other libraries.)
Change-Id: I344a3d07e146999e154824837ed95db2b9879356
cc6240aeb2