Fix typo in CMakeLists. (openscad#5375)

USE_GLEW not mutually exclusive itself but with USE_GLAD

Author: hzeller

CMakeLists.txt

@@ -41,7 +41,7 @@ option(ENABLE_EGL "Enable EGL support if available" ON)
 option(ENABLE_GLX "Enable GLX support if available" ON)
 # For now, we'll default to whatever OpenCSG uses (>=1.6 -> GLAD, <1.6 -> GLEW)
 option(USE_GLAD "Use GLAD. Mutually exclusive from USE_GLEW" OFF)
-option(USE_GLEW "Use GLEW. Mutually exclusive from USE_GLEW" OFF)
+option(USE_GLEW "Use GLEW. Mutually exclusive from USE_GLAD" OFF)
 option(NULLGL "Build without OpenGL, (implies HEADLESS=ON) " OFF)
 option(IDPREFIX "Prefix CSG nodes with index # (debugging purposes only, will break node cache)" OFF)
 option(PROFILE "Enable compiling with profiling / test coverage instrumentation" OFF)