Fix missing E2SM-RC message forward

E2SM-RC RRC message forwarding (e.g., to signal a new UE, measurement
reports, ...) was broken since commit d6c29b2d2c, as we accidentally
removed the E2_AGENT compilation definition from RRC layer.

Although this commit fixes the mentioned issue, it also causes undefined
references to functions defined in ran_func_rc.c file.  Therefore, we
add a hack that provides the definition, and abort if we ever hit these
functions, which in theory should not happen.

Future cleanup should avoid linking in RRC and other layers into
simulators.

Fixes: d6c29b2d2c ("Fix E2_AGENT linking w.r.t. simulators ")

CMakeLists.txt

@@ -464,6 +464,9 @@ target_include_directories(f1ap PUBLIC F1AP_DIR)
 target_link_libraries(f1ap PUBLIC asn1_f1ap GTPV1U)
 target_link_libraries(f1ap PRIVATE ngap nr_rrc HASHTABLE f1ap_lib)
 target_include_directories(f1ap PRIVATE ${F1AP_DIR}/lib)
+if(E2_AGENT)
+  target_compile_definitions(f1ap PRIVATE E2_AGENT)
+endif()
 
 # LPP
 ##############
@@ -1288,6 +1291,9 @@ add_library(L2
   )
 target_link_libraries(L2 PRIVATE x2ap s1ap lte_rrc m2ap)
 target_link_libraries(L2 PRIVATE asn1_lte_rrc_hdrs asn1_nr_rrc_hdrs)
+if(E2_AGENT)
+  target_compile_definitions(L2 PRIVATE ${E2AP_VERSION} ${KPM_VERSION} E2_AGENT)
+endif()
 
 add_library(MAC_UE_NR ${MAC_NR_SRC_UE})
 target_link_libraries(MAC_UE_NR PRIVATE asn1_lte_rrc_hdrs asn1_nr_rrc_hdrs PUBLIC nr_ue_power_procedures nr_ue_ra_procedures)
@@ -1303,6 +1309,9 @@ add_library(L2_NR
 target_link_libraries(L2_NR PRIVATE ds alg)
 target_link_libraries(L2_NR PRIVATE f1ap_lib)
 target_include_directories(L2_NR PRIVATE ${F1AP_DIR}/lib)
+if(E2_AGENT)
+  target_compile_definitions(L2_NR PRIVATE ${E2AP_VERSION} ${KPM_VERSION} E2_AGENT)
+endif()
 
 add_library(e1_if
   ${NR_RRC_DIR}/cucp_cuup_direct.c