internal/egl: remove unused field

Signed-off-by: Elias Naur <mail@eliasnaur.com>

internal/egl/egl.go

@@ -19,7 +19,6 @@ type Context struct {
 	eglCtx        *eglContext
 	eglSurf       _EGLSurface
 	width, height int
-	refreshFBO    bool
 }
 
 type eglContext struct {
@@ -126,7 +125,6 @@ func (c *Context) CreateSurface(win NativeWindowType, width, height int) error {
 	c.eglSurf = eglSurf
 	c.width = width
 	c.height = height
-	c.refreshFBO = true
 	return err
 }