[x265] fix: segmentation fault --tune zerolatency

[Satoshi Nakagawa]

# HG changeset patch
# User Satoshi Nakagawa <nakagawa424 at oki.com>
# Date 1400725081 -32400
#      Thu May 22 11:18:01 2014 +0900
# Node ID 918e875f261751bcebc366e82b219221e6a998ee
# Parent  dadb646a7266f377cbfa33747ecb0a97f50a00f9
fix: segmentation fault --tune zerolatency

diff -r dadb646a7266 -r 918e875f2617 source/encoder/slicetype.cpp
--- a/source/encoder/slicetype.cpp	Wed May 21 11:23:29 2014 -0500
+++ b/source/encoder/slicetype.cpp	Thu May 22 11:18:01 2014 +0900
@@ -420,7 +420,7 @@
     }
 
     /* calculate the frame costs ahead of time for estimateFrameCost while we still have lowres */
-    if (param->rc.rateControlMode != X265_RC_CQP)
+    if (param->rc.rateControlMode != X265_RC_CQP && maxSearch > 0)
     {
         int p0, p1, b;