modules: mark EGL/GLES *_LIBRARY and *_INCLUDE_DIR vars as advanced.

Not sure why that wasn't done here. It only inflates the CMake option
list as 90% of the people don't need to touch these.

modules/FindEGL.cmake

@@ -82,3 +82,5 @@ if(NOT TARGET EGL::EGL)
     set_target_properties(EGL::EGL PROPERTIES
         INTERFACE_INCLUDE_DIRECTORIES ${EGL_INCLUDE_DIR})
 endif()
+
+mark_as_advanced(EGL_LIBRARY EGL_INCLUDE_DIR)

modules/FindOpenGLES2.cmake

@@ -74,3 +74,5 @@ if(NOT TARGET OpenGLES2::OpenGLES2)
             IMPORTED_LOCATION ${OPENGLES2_LIBRARY})
     endif()
 endif()
+
+mark_as_advanced(OPENGLES2_LIBRARY)

modules/FindOpenGLES3.cmake

@@ -88,3 +88,5 @@ if(NOT TARGET OpenGLES3::OpenGLES3)
             INTERFACE_LINK_OPTIONS "SHELL:-s USE_WEBGL2=1")
     endif()
 endif()
+
+mark_as_advanced(OPENGLES3_LIBRARY)