Link targets that need RRC ASN.1 headers to header-only library

Most targets don't need the symbols from the compiled RRC ASN.1
libraries, but only the headers. In particular when compiling individual
libraries (e.g., for tests), linking the full library makes the RRC
ASN.1 libraries compile and link, when they are not needed (only headers
are needed).

For libraries that can do without these headers, don't link them.

openair2/E1AP/CMakeLists.txt

@@ -3,5 +3,5 @@ add_subdirectory(MESSAGES)
 add_library(e1ap e1ap.c e1ap_common.c e1ap_api.c)
 target_link_libraries(e1ap
                       PUBLIC asn1_e1ap f1ap
-                      PRIVATE asn1_nr_rrc asn1_lte_rrc asn1_f1ap UTIL e1_pdcp_if e1_if)
+                      PRIVATE asn1_nr_rrc_hdrs asn1_lte_rrc_hdrs asn1_f1ap UTIL e1_pdcp_if e1_if)
 target_include_directories(e1ap PUBLIC ${CMAKE_CURRENT_DIR})