qsvenc: remove vcm option on Linux

1. vcm mode is only available for H264.
2. vcm is not supported on Linux, but it is shown when run "./avconv -h
encoder=h264_qsv |grep vcm". This shouldn't happen.
Signed-off-by: Zhong Li <zhong.li@intel.com>
Signed-off-by: Maxym Dmytrychenko <maxim.d33@gmail.com>

libavcodec/qsvenc.h

@@ -81,7 +81,6 @@
 { "off", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = MFX_LOOKAHEAD_DS_OFF }, INT_MIN, INT_MAX,                                          VE, "la_ds" }, \
 { "2x", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = MFX_LOOKAHEAD_DS_2x }, INT_MIN, INT_MAX,                                            VE, "la_ds" }, \
 { "4x", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = MFX_LOOKAHEAD_DS_4x }, INT_MIN, INT_MAX,                                            VE, "la_ds" }, \
-{ "vcm",      "Use the video conferencing mode ratecontrol",  OFFSET(qsv.vcm),      AV_OPT_TYPE_INT, { .i64 = 0  },  0, 1,         VE },        \
 { "rdo",            "Enable rate distortion optimization",    OFFSET(qsv.rdo),            AV_OPT_TYPE_INT, { .i64 = -1 }, -1,          1, VE }, \
 { "max_frame_size", "Maximum encoded frame size in bytes",    OFFSET(qsv.max_frame_size), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, UINT16_MAX, VE }, \
 { "max_slice_size", "Maximum encoded slice size in bytes",    OFFSET(qsv.max_slice_size), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, UINT16_MAX, VE }, \

libavcodec/qsvenc_h264.c

@@ -68,6 +68,9 @@ static const AVOption options[] = {
     QSV_COMMON_OPTS
 
     { "cavlc",          "Enable CAVLC",                           OFFSET(qsv.cavlc),          AV_OPT_TYPE_INT, { .i64 = 0 },   0,          1, VE },
+#if QSV_HAVE_VCM
+    { "vcm",      "Use the video conferencing mode ratecontrol",  OFFSET(qsv.vcm),      AV_OPT_TYPE_INT, { .i64 = 0  },  0, 1,         VE },
+#endif
     { "idr_interval", "Distance (in I-frames) between IDR frames", OFFSET(qsv.idr_interval), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, VE },
     { "single_sei_nal_unit",    "Put all the SEI messages into one NALU",        OFFSET(qsv.single_sei_nal_unit),     AV_OPT_TYPE_INT, { .i64 = -1 }, -1,          1, VE },
     { "max_dec_frame_buffering", "Maximum number of frames buffered in the DPB", OFFSET(qsv.max_dec_frame_buffering), AV_OPT_TYPE_INT, { .i64 = 0 },   0, UINT16_MAX, VE },