Update header includes

Many files include unnecessary headers and don't include headers which
are actually used. Because of that combined with the fact that OsmoPCU
is a mixture of C and C++, it makes it hard to modularize code. Fix
this (using iwyu [1] tool):

* add missing headers
* remove unused headers

[1] https://include-what-you-use.org/

Related: OS#1539
Change-Id: I8c9f488a43b099c72b2d30d3245e7ba50872fc00

1 files changed, 0 insertions, 1 deletions

diff --git a/src/sba.h b/src/sba.h
index d2d3106e..27dae212 100644
--- a/src/sba.h
+++ b/src/sba.h
@@ -27,7 +27,6 @@ extern "C" {
 }
 
 struct BTS;
-class PollController;
 struct gprs_rlcmac_pdch;
 
 /*