utils/brmake: fix shellcheck errors

In utils/brmake line 6:
    local found ret start d h m mf
          ^---^ SC2034: found appears unused. Verify use (or export if used externally).

In utils/brmake line 16:
    > >( while read line; do
               ^--^ SC2162: read without -r will mangle backslashes.

For both, the suggestions from shellcheck can be applied.

Signed-off-by: Arnout Vandecappelle <arnout@mind.be>
(cherry picked from commit dc364c6ae6)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

utils/brmake

@@ -3,7 +3,7 @@
 # License: WTFPL, https://spdx.org/licenses/WTFPL.html
 
 main() {
-    local found ret start d h m mf
+    local ret start d h m mf
 
     if ! which unbuffer >/dev/null 2>&1; then
         printf "you need to install 'unbuffer' (from package expect or expect-dev)\n" >&2
@@ -13,7 +13,7 @@ main() {
     start=${SECONDS}
 
     ( exec 2>&1; unbuffer make "${@}"; ) \
-    > >( while read line; do
+    > >( while read -r line; do
              printf "%(%Y-%m-%dT%H:%M:%S)T %s\n" -1 "${line}"
          done \
          |tee -a br.log \