sigProcLib: Remove heap based signal vector allocations
sigProcLib: Remove heap based signal vector allocations

The osmo-trx internals rely heavily on dynamic alloction of
I/Q signal vectors. In a number of cases there is no reason
to to use dynamic rather than stack based allocation. Convert
these cases accordingly.

Change-Id: If53da1bf77b5944b6117765fa98ce12e1ccdeede

ttsou/osmo-trx,ttsou/osmo-trx,osmocom/osmo-trx,osmocom/osmo-trx,osmocom/osmo-trx,ttsou/osmo-trx,ttsou/osmo-trx,osmocom/osmo-trx