configure: fix --disable-v4l2-m2m can't work

Use the command ./configure with/without --disable-v4l2-m2m test.
Reviewed-by: Aman Gupta <aman@tmm1.net>
Signed-off-by: Jun Zhao <barryjzhao@tencent.com>

configure

@@ -6446,19 +6446,21 @@ pod2man --help     > /dev/null 2>&1 && enable pod2man   || disable pod2man
 rsync --help 2> /dev/null | grep -q 'contimeout' && enable rsync_contimeout || disable rsync_contimeout
 
 # check V4L2 codecs available in the API
-check_headers linux/fb.h
-check_headers linux/videodev2.h
-test_code cc linux/videodev2.h "struct v4l2_frmsizeenum vfse; vfse.discrete.width = 0;" && enable_sanitized struct_v4l2_frmivalenum_discrete
-check_cc v4l2_m2m linux/videodev2.h "int i = V4L2_CAP_VIDEO_M2M_MPLANE | V4L2_CAP_VIDEO_M2M | V4L2_BUF_FLAG_LAST;"
-check_cc vc1_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_VC1_ANNEX_G;"
-check_cc mpeg1_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_MPEG1;"
-check_cc mpeg2_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_MPEG2;"
-check_cc mpeg4_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_MPEG4;"
-check_cc hevc_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_HEVC;"
-check_cc h263_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_H263;"
-check_cc h264_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_H264;"
-check_cc vp8_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_VP8;"
-check_cc vp9_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_VP9;"
+if enabled v4l2_m2m; then
+    check_headers linux/fb.h
+    check_headers linux/videodev2.h
+    test_code cc linux/videodev2.h "struct v4l2_frmsizeenum vfse; vfse.discrete.width = 0;" && enable_sanitized struct_v4l2_frmivalenum_discrete
+    check_cc v4l2_m2m linux/videodev2.h "int i = V4L2_CAP_VIDEO_M2M_MPLANE | V4L2_CAP_VIDEO_M2M | V4L2_BUF_FLAG_LAST;"
+    check_cc vc1_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_VC1_ANNEX_G;"
+    check_cc mpeg1_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_MPEG1;"
+    check_cc mpeg2_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_MPEG2;"
+    check_cc mpeg4_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_MPEG4;"
+    check_cc hevc_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_HEVC;"
+    check_cc h263_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_H263;"
+    check_cc h264_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_H264;"
+    check_cc vp8_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_VP8;"
+    check_cc vp9_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_VP9;"
+fi
 
 check_headers sys/videoio.h
 test_code cc sys/videoio.h "struct v4l2_frmsizeenum vfse; vfse.discrete.width = 0;" && enable_sanitized struct_v4l2_frmivalenum_discrete