cmake: generate rtcd headers in config subdir.

Move rtcd header outputs to config subdir of config dir,
and update include sites.

Change-Id: I25c5f1808a091f3727934adc274637ebdcdcb1cf
diff --git a/test/reconinter_test.cc b/test/reconinter_test.cc
index 58d04f5..2f4dc3a 100644
--- a/test/reconinter_test.cc
+++ b/test/reconinter_test.cc
@@ -14,7 +14,7 @@
 #include <string.h>
 
 #include "config/aom_config.h"
-#include "./av1_rtcd.h"
+#include "config/av1_rtcd.h"
 
 #include "aom_ports/mem.h"
 #include "av1/common/scan.h"