Fix SC2155 issues (#1975)

I forgot to include this in
#1971 (made the change locally
and forgot to push before merging).

I originally suppressed these lints because I misunderstood how `set -o
errexit` interacts with `readonly`. I thought a failure would still
bring down the whole script, but that's not the case. So instead of
suppressing the lint, I fixed the issue.

build_tools/github_actions/lint_buildifier.sh

@@ -23,8 +23,8 @@ if ! command -v buildifier &> /dev/null; then
   exit 1
 fi
 
-# shellcheck disable=SC2155
-readonly SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+readonly SCRIPT_DIR
 readonly STABLEHLO_ROOT_DIR="${SCRIPT_DIR}/../.."
 
 cd "$STABLEHLO_ROOT_DIR"

build_tools/github_actions/lint_markdown.sh

@@ -27,8 +27,8 @@ if [[ $# -gt 2 ]] ; then
   exit 1
 fi
 
-# shellcheck disable=SC2155
-readonly SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+readonly SCRIPT_DIR
 readonly STABLEHLO_ROOT_DIR="${SCRIPT_DIR}/../.."
 
 # These must be relative to the repo root because that's the context

build_tools/github_actions/lint_shellcheck.sh

@@ -25,8 +25,8 @@ if ! command -v shellcheck &> /dev/null; then
   exit 1
 fi
 
-# shellcheck disable=SC2155
-readonly SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+readonly SCRIPT_DIR
 readonly STABLEHLO_ROOT_DIR="${SCRIPT_DIR}/../.."
 
 cd "$STABLEHLO_ROOT_DIR"