lib: Move failure handler structs and typedefs to failures-private.h

Also change the function typedefs to be non-pointers, like they usually are
in Dovecot code.

src/lib/Makefile.am

@@ -191,6 +191,7 @@ headers = \
 	event-log.h \
 	execv-const.h \
 	failures.h \
+	failures-private.h \
 	fd-util.h \
 	fdatasync-path.h \
 	fdpass.h \

src/lib/failures-private.h

@@ -0,0 +1,26 @@
+#ifndef FAILURES_PRIVATE_H
+#define FAILURES_PRIVATE_H
+
+typedef int
+failure_write_to_file_t(enum log_type type, string_t *data, size_t prefix_len);
+typedef string_t *
+failure_format_str_t(const struct failure_context *ctx, size_t *prefix_len_r,
+		     const char *format, va_list args);
+typedef void failure_on_handler_failure_t(const struct failure_context *ctx);
+typedef void failure_post_handler_t(const struct failure_context *ctx);
+
+struct failure_handler_vfuncs {
+	failure_write_to_file_t *write;
+	failure_format_str_t *format;
+	failure_on_handler_failure_t *on_handler_failure;
+	failure_post_handler_t *post_handler;
+};
+
+struct failure_handler_config {
+	int fatal_err_reset;
+	struct failure_handler_vfuncs *v;
+};
+
+extern struct failure_handler_config failure_handler;
+
+#endif

src/lib/failures.c

@@ -10,6 +10,7 @@
 #include "backtrace-string.h"
 #include "printf-format-fix.h"
 #include "write-full.h"
+#include "failures-private.h"
 
 #include <unistd.h>
 #include <fcntl.h>
@@ -60,13 +61,6 @@ static void log_prefix_add(const struct failure_context *ctx, string_t *str);
 static void i_failure_send_option(const char *key, const char *value);
 static int internal_send_split(string_t *full_str, size_t prefix_len);
 
-typedef int (*failure_write_to_file_t)(enum log_type type, string_t *data, size_t prefix_len);
-typedef string_t *(*failure_format_str_t)(const struct failure_context *ctx,
-				  size_t *prefix_len_r, const char *format,
-				  va_list args);
-typedef void (*failure_on_handler_failure_t)(const struct  failure_context *ctx);
-typedef void (*failure_post_handler_t)(const struct  failure_context *ctx);
-
 static string_t * ATTR_FORMAT(3, 0) default_format(const struct failure_context *ctx,
 						   size_t *prefix_len_r ATTR_UNUSED,
 						   const char *format,
@@ -223,18 +217,6 @@ static void internal_post_handler(const struct failure_context *ctx ATTR_UNUSED)
 {
 }
 
-struct failure_handler_vfuncs {
-	failure_write_to_file_t write;
-	failure_format_str_t format;
-	failure_on_handler_failure_t on_handler_failure;
-	failure_post_handler_t post_handler;
-};
-
-struct failure_handler_config {
-	int fatal_err_reset;
-	struct failure_handler_vfuncs *v;
-};
-
 static struct failure_handler_vfuncs default_handler_vfuncs = {
 	.write = &default_write,
 	.format = &default_format,