scripts: handle egrep deprecation notice

Change scripts/lint to handle the deprecation warning about egrep that's
reported on recent non-Debian systems by checking the exit code
explicitly instead of merely checking for the presence of output.

Fixes #3635

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.22.0
+FROM --platform=linux/amd64 golang:1.22.3
 
 RUN apt-get update -y --allow-insecure-repositories && \
   apt-get install -y build-essential curl git libncurses5-dev python3-pip && \

scripts/lint

@@ -54,8 +54,8 @@ lint=$(sh "$vimdir/share/vim/vimgo/pack/vim-go/start/vim-vimlint/bin/vimlint.sh"
   -c func_abort=1 \
   -e EVL110=1 -e EVL103=1 -e EVL104=1 -e EVL102=1 \
   "$vimgodir" \
-  2>&1 ||:)
-if [ -n "$lint" ]; then
+  2>&1)
+if [ "$?" -ne 2 ]; then
   echo "FAILED"
   echo "$lint"
   echo