Fix buffer overflow.

Bug chromium:712624

Change-Id: I8e7813aac44c9fef1a2311be550da8cea5a65d16
Reviewed-on: https://swiftshader-review.googlesource.com/9330
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>

src/Reactor/SubzeroReactor.cpp

diff --git a/src/Reactor/SubzeroReactor.cpp b/src/Reactor/SubzeroReactor.cpp
index 30f4714..b4a7db2 100644
--- a/src/Reactor/SubzeroReactor.cpp
+++ b/src/Reactor/SubzeroReactor.cpp
@@ -1152,7 +1152,8 @@
 	{
 		if(Ice::isVectorType(T(Ty)))
 		{
-			int64_t c[4] = {0, 0, 0, 0};
+			assert(Ice::typeNumElements(T(Ty)) <= 16);
+			int64_t c[16] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
 			return createConstantVector(c, Ty);
 		}
 		else