Allow setting bitrate modes 1-5 too

These correspond to different VBR modes.

libAACenc/src/aacenc_lib.cpp

@@ -1599,6 +1599,11 @@ AACENC_ERROR aacEncoder_SetParam(
         if (settings->userBitrateMode != value) {
             switch ( value ) {
               case 0:
+              case 1:
+              case 2:
+              case 3:
+              case 4:
+              case 5:
               case 8:
                 settings->userBitrateMode = value;
                 hAacEncoder->InitFlags |= AACENC_INIT_CONFIG | AACENC_INIT_TRANSPORT;