Name public API structs

include/secp256k1_recovery.h

@@ -21,7 +21,7 @@ extern "C" {
  *  recoverability) will have identical representation, so they can be
  *  memcmp'ed.
  */
-typedef struct {
+typedef struct secp256k1_ecdsa_recoverable_signature {
     unsigned char data[65];
 } secp256k1_ecdsa_recoverable_signature;