main/pbx: Move pbx_builtin dialplan applications to pbx_builtins.c

We joked about splitting pbx.c into multiple files but this first step was
fairly easy.  All of the pbx_builtin dialplan applications have been moved
into pbx_builtins.c and a new pbx_private.h file was added. load_pbx_builtins()
is called by asterisk.c just after load_pbx().

A few functions were renamed and are cross-exposed between the 2 source files.

Change-Id: I87066be3dbf7f5822942ac1449d98cc43fc7561a

include/asterisk/_private.h

@@ -17,6 +17,7 @@
 
 int load_modules(unsigned int);		/*!< Provided by loader.c */
 int load_pbx(void);			/*!< Provided by pbx.c */
+int load_pbx_builtins(void);	/*!< Provided by pbx_builtins.c */
 int init_logger(void);			/*!< Provided by logger.c */
 void close_logger(void);		/*!< Provided by logger.c */
 void logger_queue_start(void);		/*!< Provided by logger.c */

main/asterisk.c

@@ -4595,6 +4595,11 @@ static void asterisk_daemon(int isroot, const char *runuser, const char *rungrou
 		exit(1);
 	}
 
+	if (load_pbx_builtins()) {
+		printf("Failed: load_pbx_builtins\n%s", term_quit());
+		exit(1);
+	}
+
 	if (ast_local_init()) {
 		printf("Failed: ast_local_init\n%s", term_quit());
 		exit(1);

main/pbx_private.h

@@ -0,0 +1,37 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2015 Fairview 5 Engineering, LLC
+ *
+ * George Joseph <george.joseph@fairview5.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*! \file
+ * \brief Private include file for pbx
+ */
+
+#ifndef _PBX_PRIVATE_H
+#define _PBX_PRIVATE_H
+
+/*! pbx.c functions needed by pbx_builtins.c */
+int raise_exception(struct ast_channel *chan, const char *reason, int priority);
+void wait_for_hangup(struct ast_channel *chan, const void *data);
+void set_ext_pri(struct ast_channel *c, const char *exten, int pri);
+
+/*! pbx_builtins.c functions needed by pbx.c */
+int indicate_congestion(struct ast_channel *, const char *);
+int indicate_busy(struct ast_channel *, const char *);
+
+#define VAR_BUF_SIZE 4096
+
+#endif /* _PBX_PRIVATE_H */