Fix build.

src/nvtt/bc6h/utils.cpp

@@ -15,6 +15,8 @@ See the License for the specific language governing permissions and limitations
 #include "utils.h"
 #include <math.h>
 
+using namespace nv;
+
 static int denom7_weights_64[] = {0, 9, 18, 27, 37, 46, 55, 64};										// divided by 64
 static int denom15_weights_64[] = {0, 4, 9, 13, 17, 21, 26, 30, 34, 38, 43, 47, 51, 55, 60, 64};		// divided by 64
 

src/nvtt/bc6h/zohone.cpp

@@ -18,11 +18,14 @@ See the License for the specific language governing permissions and limitations
 #include "zoh.h"
 #include "utils.h"
 
+#include "nvmath/Vector.h"
 #include "nvmath/Fitting.h"
 
 #include <string.h> // strlen
 #include <float.h> // FLT_MAX
 
+using namespace nv;
+
 #define NINDICES	16
 #define	INDEXBITS	4
 #define	HIGH_INDEXBIT	(1<<(INDEXBITS-1))

src/nvtt/bc6h/zohtwo.cpp

@@ -47,6 +47,7 @@ See the License for the specific language governing permissions and limitations
 #include <string.h> // strlen
 #include <float.h> // FLT_MAX
 
+using namespace nv;
 
 #define NINDICES	8
 #define	INDEXBITS	3