improve handling of API calls provided by loaded modules through use of some GCC features; this makes app_stack's usage of AGI APIs even cleaner, and will allow it to work 'as expected' either with or without res_agi being loaded

reviewed at http://reviewboard.digium.com/r/62



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@159631 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_agi.c

@@ -51,7 +51,6 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #include "asterisk/utils.h"
 #include "asterisk/lock.h"
 #include "asterisk/strings.h"
-#include "asterisk/agi.h"
 #include "asterisk/manager.h"
 #include "asterisk/ast_version.h"
 #include "asterisk/speech.h"
@@ -60,6 +59,9 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #include "asterisk/term.h"
 #include "asterisk/xmldoc.h"
 
+#define AST_API_MODULE
+#include "asterisk/agi.h"
+
 /*** DOCUMENTATION
 	<agi name="answer" language="en_US">
 		<synopsis>