Let DISABLE_TRELLISQ_SEARCH configurable

Change-Id: I48ebf352c6c28e5c0c0e477b24828f0e3fe1dedb

av1/encoder/rdopt.c

diff --git a/av1/encoder/rdopt.c b/av1/encoder/rdopt.c
index bbba1af..b81b8c8 100644
--- a/av1/encoder/rdopt.c
+++ b/av1/encoder/rdopt.c
@@ -171,7 +171,9 @@
 // Setting this to 1 will disable trellis optimization within the
 // transform search. Trellis optimization will still be applied
 // in the final encode.
+#ifndef DISABLE_TRELLISQ_SEARCH
 #define DISABLE_TRELLISQ_SEARCH 0
+#endif
 
 const double ADST_FLIP_SVM[8] = { -6.6623, -2.8062, -3.2531, 3.1671,    // vert
                                   -7.7051, -3.2234, -3.6193, 3.4533 };  // horz