credentials: suffix the callbacks with `_cb`

The credential callbacks should match the other callback naming
conventions, using the `_cb` suffix instead of a `_callback` suffix.

include/git2/deprecated.h

@@ -246,6 +246,21 @@ GIT_EXTERN(void) giterr_set_oom(void);
 
 /**@}*/
 
+/** @name Deprecated Credential Callback Types
+ *
+ * These types are retained for backward compatibility.  The newer
+ * versions of these values should be preferred in all new code.
+ *
+ * There is no plan to remove these backward compatibility values at
+ * this time.
+ */
+/**@{*/
+
+typedef git_cred_sign_cb git_cred_sign_callback;
+typedef git_cred_ssh_interactive_cb git_cred_ssh_interactive_callback;
+
+/**@}*/
+
 /** @name Deprecated Transfer Progress Types
  *
  * These types are retained for backward compatibility.  The newer

include/git2/transport.h

@@ -165,8 +165,8 @@ typedef struct _LIBSSH2_USERAUTH_KBDINT_PROMPT LIBSSH2_USERAUTH_KBDINT_PROMPT;
 typedef struct _LIBSSH2_USERAUTH_KBDINT_RESPONSE LIBSSH2_USERAUTH_KBDINT_RESPONSE;
 #endif
 
-typedef int GIT_CALLBACK(git_cred_sign_callback)(LIBSSH2_SESSION *session, unsigned char **sig, size_t *sig_len, const unsigned char *data, size_t data_len, void **abstract);
-typedef void GIT_CALLBACK(git_cred_ssh_interactive_callback)(const char* name, int name_len, const char* instruction, int instruction_len, int num_prompts, const LIBSSH2_USERAUTH_KBDINT_PROMPT* prompts, LIBSSH2_USERAUTH_KBDINT_RESPONSE* responses, void **abstract);
+typedef int GIT_CALLBACK(git_cred_sign_cb)(LIBSSH2_SESSION *session, unsigned char **sig, size_t *sig_len, const unsigned char *data, size_t data_len, void **abstract);
+typedef void GIT_CALLBACK(git_cred_ssh_interactive_cb)(const char* name, int name_len, const char* instruction, int instruction_len, int num_prompts, const LIBSSH2_USERAUTH_KBDINT_PROMPT* prompts, LIBSSH2_USERAUTH_KBDINT_RESPONSE* responses, void **abstract);
 
 /**
  * A ssh key from disk
@@ -185,7 +185,7 @@ typedef struct git_cred_ssh_key {
 typedef struct git_cred_ssh_interactive {
 	git_cred parent;
 	char *username;
-	git_cred_ssh_interactive_callback prompt_callback;
+	git_cred_ssh_interactive_cb prompt_callback;
 	void *payload;
 } git_cred_ssh_interactive;
 
@@ -197,7 +197,7 @@ typedef struct git_cred_ssh_custom {
 	char *username;
 	char *publickey;
 	size_t publickey_len;
-	git_cred_sign_callback sign_callback;
+	git_cred_sign_cb sign_callback;
 	void *payload;
 } git_cred_ssh_custom;
 
@@ -262,7 +262,7 @@ GIT_EXTERN(int) git_cred_ssh_key_new(
 GIT_EXTERN(int) git_cred_ssh_interactive_new(
 	git_cred **out,
 	const char *username,
-	git_cred_ssh_interactive_callback prompt_callback,
+	git_cred_ssh_interactive_cb prompt_callback,
 	void *payload);
 
 /**
@@ -300,7 +300,7 @@ GIT_EXTERN(int) git_cred_ssh_custom_new(
 	const char *username,
 	const char *publickey,
 	size_t publickey_len,
-	git_cred_sign_callback sign_callback,
+	git_cred_sign_cb sign_callback,
 	void *payload);
 
 /**

src/transports/cred.c

@@ -264,7 +264,7 @@ static int git_cred_ssh_key_type_new(
 int git_cred_ssh_interactive_new(
 	git_cred **out,
 	const char *username,
-	git_cred_ssh_interactive_callback prompt_callback,
+	git_cred_ssh_interactive_cb prompt_callback,
 	void *payload)
 {
 	git_cred_ssh_interactive *c;
@@ -312,7 +312,7 @@ int git_cred_ssh_custom_new(
 	const char *username,
 	const char *publickey,
 	size_t publickey_len,
-	git_cred_sign_callback sign_callback,
+	git_cred_sign_cb sign_callback,
 	void *payload)
 {
 	git_cred_ssh_custom *c;