x264: make sure b-pyramid ain't set other than high-profile

Reported by Lotesdelere

modules/codec/x264.c

@@ -1137,11 +1137,13 @@ static int  Open ( vlc_object_t *p_this )
             p_sys->param.b_cabac = 0;
             p_sys->param.i_bframe = 0;
             p_sys->param.analyse.i_weighted_pred = X264_WEIGHTP_NONE;
+            p_sys->param.i_bframe_pyramid = X264_B_PYRAMID_NONE;
         }
         else if (!strcasecmp( psz_val, "main" ) )
         {
             msg_Dbg( p_enc, "Limiting to main-profile");
             p_sys->param.analyse.b_transform_8x8 = 0;
+            p_sys->param.i_bframe_pyramid = X264_B_PYRAMID_NONE;
         }
         /* high profile don't restrict stuff*/
     }