Allow linking on a GLX-less system.
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -87 +87 @@
-  find_package(OpenGL REQUIRED)
+  find_package(OpenGL REQUIRED COMPONENTS OpenGL )
@@ -195 +195 @@
-	set( OPENGL_LDFLAGS  ${OPENGL_LIBRARIES} )
+	set( OPENGL_LDFLAGS  OpenGL::OpenGL )