Make layer activation via CreateDevice struct or env variable

Also finish making all activated layers per icd and per gpu.
diff --git a/loader/loader.h b/loader/loader.h
index d819142..47802d4 100644
--- a/loader/loader.h
+++ b/loader/loader.h
@@ -40,6 +40,6 @@
 #  define LOADER_EXPORT
 #endif
 
-extern XGL_UINT ActivateLayers(XGL_PHYSICAL_GPU *gpu);
-#define MAX_LAYER_LIBRARIES 16
+extern XGL_UINT ActivateLayers(XGL_PHYSICAL_GPU *gpu, const XGL_DEVICE_CREATE_INFO* pCreateInfo);
+#define MAX_LAYER_LIBRARIES 64
 #endif /* LOADER_H */