Replace index_in_[sub]str_array with index_in_[sub]strings,

which scans thru "abc\0def\0123\0\0" type strings. Saves 250 bytes.

   text    data     bss     dec     hex filename
 781266    1328   11844  794438   c1f46 busybox_old
 781010    1328   11844  794182   c1e46 busybox_unstripped

libbb/dump.c

@@ -449,7 +449,7 @@ static const char conv_str[] =
 	"\r\\r\0"
 	"\t\\t\0"
 	"\v\\v\0"
-	"\0";
+	;
 
 
 static void conv_c(PR * pr, unsigned char * p)