certificate: Return signature scheme and parameters from issued_by() method

This also required some include restructuring (avoid including library.h
in headers) to avoid unresolvable circular dependencies.

src/libstrongswan/crypto/hashers/hasher.h

@@ -27,7 +27,6 @@
 typedef enum hash_algorithm_t hash_algorithm_t;
 typedef struct hasher_t hasher_t;
 
-#include <library.h>
 #include <crypto/prfs/prf.h>
 #include <crypto/signers/signer.h>
 #include <credentials/keys/public_key.h>

src/libstrongswan/crypto/prfs/prf.h

@@ -25,7 +25,8 @@
 typedef enum pseudo_random_function_t pseudo_random_function_t;
 typedef struct prf_t prf_t;
 
-#include <library.h>
+#include <utils/utils.h>
+#include <utils/chunk.h>
 
 /**
  * Pseudo random function, as in IKEv2 RFC 3.3.2.

src/libstrongswan/crypto/signers/signer.h

@@ -25,7 +25,8 @@
 typedef enum integrity_algorithm_t integrity_algorithm_t;
 typedef struct signer_t signer_t;
 
-#include <library.h>
+#include <utils/utils.h>
+#include <utils/chunk.h>
 
 /**
  * Integrity algorithm, as in IKEv2 RFC 3.3.2.