[COIL] Change code search type links from master to HEAD for build_library

See this doc: http://go/chromiumos-coil-change for more info

Bug: 1214702
Change-Id: I67c94ab76b4a7ded5c6709dffaa1faba81da146a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/2928150
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: My Nguyen <myy@chromium.org>
Tested-by: My Nguyen <myy@chromium.org>
diff --git a/build_library/ext2_sb_util.sh b/build_library/ext2_sb_util.sh
index 65380f6..52b5446 100644
--- a/build_library/ext2_sb_util.sh
+++ b/build_library/ext2_sb_util.sh
@@ -20,9 +20,9 @@
 # mount the filesystem as read-write -- only read-only[2].
 #
 # [1] 32-bit flag we are modifying:
-#  https://chromium.googlesource.com/chromiumos/third_party/kernel.git/+/master/include/linux/ext2_fs.h#l417
+#  https://chromium.googlesource.com/chromiumos/third_party/kernel.git/+/HEAD/include/linux/ext2_fs.h#l417
 # [2] Mount behavior is enforced here:
-#  https://chromium.googlesource.com/chromiumos/third_party/kernel.git/+/master/ext2/super.c#l857
+#  https://chromium.googlesource.com/chromiumos/third_party/kernel.git/+/HEAD/ext2/super.c#l857
 #
 # N.B., if the high order feature bits are used in the future, we will need to
 #       revisit this technique.