tests: fix build errors due to ImageMagick dependency

v2: tell users how to resolve the dependency on Ubuntu per Courtney's
    suggestion
diff --git a/tests/xgltestframework.cpp b/tests/xgltestframework.cpp
index ddaee19..54259c4 100644
--- a/tests/xgltestframework.cpp
+++ b/tests/xgltestframework.cpp
@@ -25,7 +25,7 @@
 //#include "ShaderLang.h"
 #include "GlslangToBil.h"
 #include <math.h>
-#include <ImageMagick/wand/MagickWand.h>
+#include <wand/MagickWand.h>
 
 // Command-line options
 enum TOptions {