Various cleanups from comments in an email from Luigi Rizzo. Thank you!

- Use a cleaner syntax for declaring the allocation macros
- Fix return value for ast_strdup/ast_strndup
- remove safe_strdup from app_macro, since ast_strup does the same thing
- fix a place in app_queue where ast_calloc+strncpy was used instead of
  ast_strdup.  If you are helping out with these conversions, please watch out
  for other places where this is done.
- add a note to the coding guidelines about the fix to app_queue


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@8065 65c4cc65-6c06-0410-ace0-fbb531ad65f3

doc/CODING-GUIDELINES

@@ -386,6 +386,10 @@ argument without generating an error.  The same code can be written as:
 	
 	newstr = ast_strdup(str);
 
+Furthermore, it is unnecessary to have code that malloc/calloc's for the length
+of a string (+1 for the terminating '\0') and then using strncpy to copy the
+copy the string into the resulting buffer.  This is the exact same thing as
+using ast_strdup.
 
 * CLI Commands
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