format.sh: Avoid exit when no files changed

This script is set to exit any time a command fails. In the case of
this line, the script unexpectedly errors out on this check to see if
any files have changed that are relevant for the `clang-format` tool.
The `grep` specifically will return non-zero in this case.

The workaround here is to catch the error and run `echo -e` instead,
which we know will succeed and the end result is what we want (the
list of changed files will be empty).

This allows the script to continue to completion, even when
`clang-format` has nothing to do.

Signed-off-by: Russell Bryant <[email protected]>

format.sh

@@ -264,7 +264,7 @@ clang_format_changed() {
     MERGEBASE="$(git merge-base origin/main HEAD)"
 
     # Get the list of changed files, excluding the specified ones
-    changed_files=$(git diff --name-only --diff-filter=ACM "$MERGEBASE" -- '*.h' '*.cpp' '*.cu' '*.cuh' | grep -vFf <(printf "%s\n" "${CLANG_FORMAT_EXCLUDES[@]}"))
+    changed_files=$(git diff --name-only --diff-filter=ACM "$MERGEBASE" -- '*.h' '*.cpp' '*.cu' '*.cuh' | (grep -vFf <(printf "%s\n" "${CLANG_FORMAT_EXCLUDES[@]}") || echo -e))
     if [ -n "$changed_files" ]; then
         echo "$changed_files" | xargs -P 5 clang-format -i
     fi