vidjil.cpp: Default seed must not be empty

Some germlines are built using the default seed (ie. xxx). Havin them build
with an empty seed is quite useless

algo/vidjil.cpp

@@ -105,7 +105,7 @@ enum { CMD_WINDOWS, CMD_CLONES, CMD_SEGMENT, CMD_GERMLINES } ;
 
 #define DEFAULT_K      0
 #define DEFAULT_W      50
-#define DEFAULT_SEED   ""
+#define DEFAULT_SEED   DEFAULT_GERMLINE_SEED
 
 #define DEFAULT_MAX_AUDITIONED 2000
 #define DEFAULT_RATIO_REPRESENTATIVE 0.5