GLM 1.0 compatibility (elalish#721)

Using glm/gtx/compatibility.hpp without GLM_ENABLE_EXPERIMENTAL has
become an error:

error: #error "GLM: GLM_GTX_compatibility is an experimental extension
               and may change in the future. Use #define GLM_ENABLE_EXPERIMENTAL
	       before including it, if you really want to use it."

src/utilities/include/public.h

@@ -13,6 +13,7 @@
 // limitations under the License.
 
 #pragma once
+#define GLM_ENABLE_EXPERIMENTAL  // needed for glm/gtx/compatibility.hpp
 #define GLM_FORCE_EXPLICIT_CTOR
 #include <glm/ext/matrix_transform.hpp>
 #include <glm/glm.hpp>