gstreamer-vaapi 1.15.90 tarball fails to build in Ubuntu 16.04 and 18.04

In the switch from 1.15.2 to 1.15.90 tarballs we found the following build failure.

gstvaapiencoder_h264.c: In function ‘ensure_control_rate_params’:
gstvaapiencoder_h264.c:2525:48: error: ‘VAEncMiscParameterRateControl {aka struct _VAEncMiscParameterRateControl}’ has no member named ‘max_qp’
     GST_VAAPI_ENCODER_VA_RATE_CONTROL (encoder).max_qp = 51;
                                                ^
Makefile:1713: recipe for target 'libgstvaapi_la-gstvaapiencoder_h264.lo' failed
make[5]: *** [libgstvaapi_la-gstvaapiencoder_h264.lo] Error 1
make[5]: *** Waiting for unfinished jobs....
gstvaapiencoder_h265.c: In function ‘ensure_control_rate_params’:
gstvaapiencoder_h265.c:1871:48: error: ‘VAEncMiscParameterRateControl {aka struct _VAEncMiscParameterRateControl}’ has no member named ‘max_qp’
     GST_VAAPI_ENCODER_VA_RATE_CONTROL (encoder).max_qp = 51;