fourier-local: stateless control modernization + HEVC strip

Compound patch carrying the fork's pre-Step-1 substrate, originally
authored by Jernej Škrabec / fourier on top of bootlin's a3c2476:

- src/h264.c + src/picture.c: V4L2_CID_MPEG_VIDEO_H264_* renamed to
  V4L2_CID_STATELESS_H264_*, struct shapes tracked to mainline
  (V4L2_CID_STATELESS_H264_DECODE_MODE/_START_CODE added to the
  passthrough shim).
- include/hevc-ctrls.h: redirect shim to <linux/v4l2-controls.h>
  (kernel-side HEVC controls now live in the canonical UAPI header).
- src/meson.build: src/h265.c / src/h265.h commented out — HEVC
  build path is excluded from this fork (RK3568 hantro G1/G2 has
  no HEVC, and the kernel-side HEVC controls have a separate
  rework in flight upstream).
- src/tiled_yuv.S: aarch64 stub for tiled_to_planar (assembly
  source was sunxi-cedrus armv7-only; aarch64 needs a stub to keep
  the build linking).
- include/h264-ctrls.h: removed (dead post-fourier — no source
  includes it; the passthrough shim's CID aliases live in the
  kernel header now).

Functionally equivalent to the prior fork master commits:
  c1f5108 V4L2_PIX_FMT_H264_SLICE rename
  4ccbfe9 Strip HEVC build path
  da9f2a5 include/h264-ctrls.h passthrough + CID aliases
  fc4bb10 src/h264.c track upstream UAPI shape
  13e9b64 src/h264.c drop num_slices field
  4d14ffb src/tiled_yuv.S aarch64 stub
  1b02c9b src/h264.c include utils.h

Folded into one commit during 2026-05-04 Step 1 reconciliation
(see ../phase0_evidence/2026-05-04/findings.md). Per-patch history
of the early fork commits preserved on the pre-step1 branch.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/v4l2.c

@@ -428,37 +428,71 @@ int v4l2_export_buffer(int video_fd, unsigned int type, unsigned int index,
 	return 0;
 }
 
-int v4l2_set_control(int video_fd, int request_fd, unsigned int id, void *data,
-		     unsigned int size)
+static int v4l2_ioctl_controls(int video_fd, int request_fd, unsigned long ioc,
+			       struct v4l2_ext_control *control_array,
+			       unsigned int num_controls)
 {
-	struct v4l2_ext_control control;
 	struct v4l2_ext_controls controls;
-	int rc;
 
-	memset(&control, 0, sizeof(control));
 	memset(&controls, 0, sizeof(controls));
 
-	control.id = id;
-	control.ptr = data;
-	control.size = size;
-
-	controls.controls = &control;
-	controls.count = 1;
+	controls.controls = control_array;
+	controls.count = num_controls;
 
 	if (request_fd >= 0) {
 		controls.which = V4L2_CTRL_WHICH_REQUEST_VAL;
 		controls.request_fd = request_fd;
 	}
 
-	rc = ioctl(video_fd, VIDIOC_S_EXT_CTRLS, &controls);
+	return ioctl(video_fd, ioc, &controls);
+}
+
+int v4l2_get_controls(int video_fd, int request_fd,
+		      struct v4l2_ext_control *control_array,
+		      unsigned int num_controls)
+{
+	int rc;
+
+	rc = v4l2_ioctl_controls(video_fd, request_fd, VIDIOC_G_EXT_CTRLS,
+				 control_array, num_controls);
 	if (rc < 0) {
-		request_log("Unable to set control: %s\n", strerror(errno));
+		request_log("Unable to get control(s): %s\n", strerror(errno));
 		return -1;
 	}
 
 	return 0;
 }
 
+int v4l2_set_controls(int video_fd, int request_fd,
+		      struct v4l2_ext_control *control_array,
+		      unsigned int num_controls)
+{
+	int rc;
+
+	rc = v4l2_ioctl_controls(video_fd, request_fd, VIDIOC_S_EXT_CTRLS,
+				 control_array, num_controls);
+	if (rc < 0) {
+		request_log("Unable to set control(s): %s\n", strerror(errno));
+		return -1;
+	}
+
+	return 0;
+}
+
+int v4l2_set_control(int video_fd, int request_fd, unsigned int id, void *data,
+		     unsigned int size)
+{
+	struct v4l2_ext_control control;
+
+	memset(&control, 0, sizeof(control));
+
+	control.id = id;
+	control.ptr = data;
+	control.size = size;
+
+	return v4l2_set_controls(video_fd, request_fd, &control, 1);
+}
+
 int v4l2_set_stream(int video_fd, unsigned int type, bool enable)
 {
 	enum v4l2_buf_type buf_type = type;