cmac+hash: change parameter types

For consistency and safety, change the CMC and HSH functions to accept
signed lengths and handle negative values as errors. Also, change the
input data type to void * to not require casting in the caller.

stubs.c

@@ -438,21 +438,20 @@ NSD_SignAndSendPacket(uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *info,
 
 #ifndef HAVE_CMAC
 
-unsigned int
+int
 CMC_GetKeyLength(CMC_Algorithm algorithm)
 {
   return 0;
 }
 
 CMC_Instance
-CMC_CreateInstance(CMC_Algorithm algorithm, const unsigned char *key, unsigned int length)
+CMC_CreateInstance(CMC_Algorithm algorithm, const unsigned char *key, int length)
 {
   return NULL;
 }
 
-unsigned int
-CMC_Hash(CMC_Instance inst, const unsigned char *in, unsigned int in_len,
-         unsigned char *out, unsigned int out_len)
+int
+CMC_Hash(CMC_Instance inst, const void *in, int in_len, unsigned char *out, int out_len)
 {
   return 0;
 }