doxygen: include all undocumented items in the API doc

Currently, files that omit the \file directive and all functions, enums,
structs lacking a doxygen style comment are completely missing from the doxygen
API docs.

Set EXTRACT_ALL = YES so that all files and code items are at least listed in
the doxygen API.

Change-Id: I39f558ec0a33a61a1fcec0554f53c8e7668733de
diff --git a/Doxyfile.coding.in b/Doxyfile.coding.in
index 28e3241..7c1a28e 100644
--- a/Doxyfile.coding.in
+++ b/Doxyfile.coding.in
@@ -318,7 +318,7 @@
 # Private class members and static file members will be hidden unless
 # the EXTRACT_PRIVATE and EXTRACT_STATIC tags are set to YES
 
-EXTRACT_ALL            = NO
+EXTRACT_ALL            = YES
 
 # If the EXTRACT_PRIVATE tag is set to YES all private members of a class
 # will be included in the documentation.