extend the code hidden by SDL_HAVE_YUV

src/render/opengl/SDL_shaders_gl.h

@@ -32,6 +32,7 @@ typedef enum {
     SHADER_SOLID,
     SHADER_RGB,
     SHADER_RGBA,
+#if SDL_HAVE_YUV
     SHADER_YUV_JPEG,
     SHADER_YUV_BT601,
     SHADER_YUV_BT709,
@@ -43,6 +44,7 @@ typedef enum {
     SHADER_NV21_JPEG,
     SHADER_NV21_BT601,
     SHADER_NV21_BT709,
+#endif
     NUM_SHADERS
 } GL_Shader;