cosmetic: convert explicit warnings to fixme/todo

We do not use this style (#warning as an issue tracker replacement) in
any other Osmocom project. Also those warnings clutter compiler output
making it harder to spot warnings for the actual code.

Change-Id: I72070e2a027e60e8b80c12ccfa23ff075434689f
diff --git a/src/gprs_rlcmac_sched.cpp b/src/gprs_rlcmac_sched.cpp
index e059ae1..2350808 100644
--- a/src/gprs_rlcmac_sched.cpp
+++ b/src/gprs_rlcmac_sched.cpp
@@ -60,7 +60,8 @@
 			|| ul_tbf->ul_ass_state ==
 				GPRS_RLCMAC_UL_ASS_SEND_ASS_REJ)
 			*ul_ass_tbf = ul_tbf;
-#warning "Is this supposed to be fair? The last TBF for each wins? Maybe use llist_add_tail and skip once we have all states?"
+/* FIXME: Is this supposed to be fair? The last TBF for each wins? Maybe use llist_add_tail and skip once we have all
+states? */
 	}
 	llist_for_each(pos, &bts->dl_tbfs()) {
 		dl_tbf = as_dl_tbf(pos->entry());