Request EGL in GLFW window creation (flutter/engine#16924)

Skia expects an EGL context, but GLFW was defaulting to non-EGL, which
causes eglGetCurrentDisplay to fail--since the context wasn't made
current via EGL--with new versions of libglvnd. (It may have worked only
by accident with previous versions).

Fixes https://github.com/flutter/flutter/issues/47954

engine/src/flutter/shell/platform/glfw/flutter_glfw.cc

@@ -139,6 +139,9 @@ static FlutterDesktopWindowControllerState* GetSavedWindowState(
 static UniqueGLFWwindowPtr CreateShareWindowForWindow(GLFWwindow* window) {
   glfwWindowHint(GLFW_DECORATED, GLFW_FALSE);
   glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);
+#if defined(__linux__)
+  glfwWindowHint(GLFW_CONTEXT_CREATION_API, GLFW_EGL_CONTEXT_API);
+#endif
   GLFWwindow* share_window = glfwCreateWindow(1, 1, "", NULL, window);
   glfwDefaultWindowHints();
   return UniqueGLFWwindowPtr(share_window, glfwDestroyWindow);
@@ -561,6 +564,9 @@ FlutterDesktopWindowControllerRef FlutterDesktopCreateWindow(
   if (window_properties.prevent_resize) {
     glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
   }
+#if defined(__linux__)
+  glfwWindowHint(GLFW_CONTEXT_CREATION_API, GLFW_EGL_CONTEXT_API);
+#endif
   state->window = UniqueGLFWwindowPtr(
       glfwCreateWindow(window_properties.width, window_properties.height,
                        window_properties.title, NULL, NULL),