Add an assert to expect_equal() to make sure people send in reasonabl…

…e widths and heights.

test_util.cpp

@@ -185,6 +185,9 @@ void expect_equal(const float *ref, const float *result, unsigned width, unsigne
 
 void expect_equal(const unsigned char *ref, const unsigned char *result, unsigned width, unsigned height, unsigned largest_difference_limit, float rms_limit)
 {
+	assert(width > 0);
+	assert(height > 0);
+
 	float *ref_float = new float[width * height];
 	float *result_float = new float[width * height];