More fixes to access and buffer compilation.

test/arrays.ink

@@ -1,5 +1,6 @@
 vertex main :: () -> float4 @position {
 	arr : [16].float4;
-	// arr[0] = float4(1,1,1);
-	return arr[0];
+	arr[0] = float4(1, 1, 1, 1);
+	pos := arr[1];
+	return pos;
 }