Enable EXTRACT_STATIC for doxygen

Set EXTRACT_STATIC as YES to make doxygen parse comments for static
functions, for example, partition search functions in encodeframe.c

Change-Id: I6402e4d2854485996d151194a75ad1c292586941
diff --git a/libs.doxy_template b/libs.doxy_template
index 34e0440..8475a40 100644
--- a/libs.doxy_template
+++ b/libs.doxy_template
@@ -491,7 +491,7 @@
 # included in the documentation.
 # The default value is: NO.
 
-EXTRACT_STATIC         = NO
+EXTRACT_STATIC         = YES
 
 # If the EXTRACT_LOCAL_CLASSES tag is set to YES, classes (and structs) defined
 # locally in source files will be included in the documentation. If set to NO,