Add: Add excerpt_size field to credentials_t

The credentials struct now has a new field for the setting
"Note/Override Excerpt Size".

This allows gvmd to cache the setting so it does not have to query the
database for every reference to a note or override in a report.

base/credentials.h

@@ -34,6 +34,8 @@ typedef struct
   ///< Dynamic Severity setting of user.
   /*@null@ */ gchar *role;
   ///< Role of user.
+  /*@null@ */ int excerpt_size;
+  ///< Note/Override Excerpt Size setting of user.
 } credentials_t;
 
 void