backend/egl: refactor eglChooseConfig's attrib_list

* the default value of EGL_SURFACE_TYPE is EGL_WINDOW_BIT so let's
remove it;
* since we're not using the stencil buffer let's set the
EGL_STENCIL_SIZE attribute to 0 to match the glXChooseFBConfig's
attrib_list and avoid getting frame buffer configurations with stencil
buffer;
* the default value of EGL_STENCIL_SIZE is 0 so let's remove it;
* since attributes are described in the alphabetical order in the
eglChooseConfig function specification, which is not very practical,
let's mimic the order they're sorted in in glXChooseFBConfig's
attrib_list.

references:
https://registry.khronos.org/EGL/sdk/docs/man/html/eglChooseConfig.xhtml

src/backend/gl/egl.c

@@ -165,15 +165,13 @@ static backend_t *egl_init(session_t *ps, xcb_window_t target) {
 	// clang-format off
 	if (eglChooseConfig(gd->display,
 	                    (EGLint[]){
-	                             EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
-	                             EGL_RENDERABLE_TYPE, EGL_OPENGL_BIT,
-	                             EGL_RED_SIZE, visual_info.red_size,
-	                             EGL_GREEN_SIZE, visual_info.green_size,
-	                             EGL_BLUE_SIZE, visual_info.blue_size,
-	                             EGL_ALPHA_SIZE, visual_info.alpha_size,
-	                             EGL_STENCIL_SIZE, 1,
-	                             EGL_CONFIG_CAVEAT, EGL_NONE,
-	                             EGL_NONE,
+	                            EGL_RED_SIZE, visual_info.red_size,
+	                            EGL_GREEN_SIZE, visual_info.green_size,
+	                            EGL_BLUE_SIZE, visual_info.blue_size,
+	                            EGL_ALPHA_SIZE, visual_info.alpha_size,
+	                            EGL_RENDERABLE_TYPE, EGL_OPENGL_BIT,
+	                            EGL_CONFIG_CAVEAT, EGL_NONE,
+	                            EGL_NONE,
 	                     }, &config, nconfigs, &nconfigs) != EGL_TRUE) {
 		log_error("Failed to choose EGL config for the root window.");
 		goto end;