scripts: remove_stale_hints: make it faster

.scripts/remove_stale_hints.sh

@@ -7,27 +7,30 @@ if [ $# -gt 0 ] && [ $1 == "list" ]; then
 	list=true
 fi
 
-declare -A files # Store all basenames in repo
-declare -A hints # Store all paths of hints in repo
+declare -A files # Store all basenames for non-hint files in repo (value = 1, this is just a set)
+declare -A hints # Store a map from hint paths into basenames (turns out basename computation was a bottleneck)
 
 trap 'RC=$?; rm -f .filelist; exit $RC' EXIT INT
 
 # Find all (normal) files, not descending into .git, and store in
 # the array. Using a pipe here would be better, but a pipe creates a
 # subshell, so changes to the variables won't have any effect in the
 # parent.
-find . -name '.git' -prune -o \( -type f \) > .filelist
+find . -name '.git' -prune -false -o \( -type f -name '*.hints' \) > .filelist
 while read f0; do
 	f="$(basename "${f0}")"
-	files[$f]=1;
-	if [[ "$f0" == *.hints ]]; then
-		hints[$f0]=1
-	fi
+	hints[$f0]=$f
+done < .filelist
+
+find . -name '.git' -prune -false -o \( -type f -not -name '*.hints' \) -printf '%f\n' > .filelist
+while read f; do
+	files[$f]=1
 done < .filelist
+
 rm -f .filelist
 
 for h0 in "${!hints[@]}"; do
-	h="$(basename "${h0}")"
+	h=${hints[$h0]}
 	h="${h%.hints}"
 	# Given a/b/c/Foo.Bar.fst.hints, if there is no Foo.Bar.fst
 	# anywhere, then delete the hint file.