Switch to a preconfigured Clang for k8 and armv7

This one reuses more of Bazel's builtin features to remain up to date
more easily, and it's easier to expand support for more platforms. This
also takes care of upgrading to a newer Clang.

This will require updating to raspios bullseye on the Raspberry Pis.
This also renames armhf-debian to armv7 to match the broader Bazel
ecosystem's name for this architecture.

Change-Id: I3e2a4f4efea43e76314ca34a9293c7b4b45edd2c
Signed-off-by: Brian Silverman <bsilver16834@gmail.com>
diff --git a/y2020/vision/camera_reader.cc b/y2020/vision/camera_reader.cc
index 64e7948..1e28e82 100644
--- a/y2020/vision/camera_reader.cc
+++ b/y2020/vision/camera_reader.cc
@@ -241,7 +241,7 @@
     cv::Mat mask;
     cv::Mat homography =
         cv::findHomography(per_image.training_points, per_image.query_points,
-                           CV_RANSAC, 3.0, mask);
+                           cv::FM_RANSAC, 3.0, mask);
 
     const int homography_feature_count = cv::countNonZero(mask);
     // If mask doesn't have enough leftover matches, skip these matches
@@ -341,7 +341,7 @@
       cv::solvePnP(per_image_good_match.training_points_3d,
                    per_image_good_match.query_points, CameraIntrinsics(),
                    CameraDistCoeffs(), R_camera_field_vec, T_camera_field,
-                   FLAGS_use_prev_pose, CV_ITERATIVE);
+                   FLAGS_use_prev_pose, cv::SOLVEPNP_ITERATIVE);
     }
 
     // We are occasionally seeing NaN in the prior estimate, so checking for