Fix asn1c double free

The UE stores PDCCH search spaces from the network in NR_BWP_PDCCH_t
struct within NR_UE_MAC_INST_t. After storing, the pointers otherSI_SS,
ra_SS and paging_SS are updated to point to the stored SS. Multiple
pointers could point to the same stored SS struct depending on
configuration. Then when the UE wants to release the SS, the pointers
are used to free the stored SS using ASN_STRUCT_RESET(). If multiple
pointers point to the same SS, calling ASN_STRUCT_RESET() on all
pointers would lead to double free. So one needs to check for dangling
pointer before freeing.

Instead of using pointers and assigning them during configuration, we
use SS id for otherSI_SS, ra_SS and paging_SS to retrieve the pointers
whenever needed. When the UE wants to release the SS, we make them -1
indicating an invalid SS id.

common/utils/oai_asn1.h

@@ -228,5 +228,9 @@ static inline uint64_t BIT_STRING_to_uint64(const BIT_STRING_t *asn) {
     free(STRUCT);                       \
     STRUCT = NULL;                      \
   } while (0)
+#define asn1cFreeSeq(ASN_DEF, LIST)                     \
+  do {                                                  \
+    ASN_STRUCT_FREE(ASN_DEF, LIST.array[--LIST.count]); \
+  } while (LIST.count > 0)                              \
 
 #endif