docs: enable local structs in doxygen output

Change-Id: I9c811d49690524f1ce5372326de67ec4ac7b09f4
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/858
Tested-by: jenkins
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>

Doxyfile.in

@@ -313,7 +313,7 @@ EXTRACT_STATIC         = YES
 # defined locally in source files will be included in the documentation.
 # If set to NO only classes defined in header files are included.
 
-EXTRACT_LOCAL_CLASSES  = NO
+EXTRACT_LOCAL_CLASSES  = YES
 
 # This flag is only useful for Objective-C code. When set to YES local
 # methods, which are defined in the implementation section but not in