extra-cmake-modules: Use associative array to recognize paths

Fixes #99308.

Use an associative array to recognize paths that have already been seen by the
host path hook. This takes advantage of fast lookup of associative array keys in
Bash. The previous solution scanned a linear array, which was accidentally
quadratic.

pkgs/development/libraries/kde-frameworks/extra-cmake-modules/setup-hook.sh

@@ -59,23 +59,24 @@ xdgDataSubdirs=( \
     "wallpapers" "applications" "desktop-directories" "mime" "appdata" "dbus-1" \
 )
 
-ecmHostPathSeen=( )
+# ecmHostPathsSeen is an associative array of the paths that have already been
+# seen by ecmHostPathHook.
+declare -gA ecmHostPathsSeen
 
-ecmUnseenHostPath() {
-    for pkg in "${ecmHostPathSeen[@]}"
-    do
-        if [ "${pkg:?}" == "$1" ]
-        then
-            return 1
-        fi
-    done
-
-    ecmHostPathSeen+=("$1")
-    return 0
+ecmHostPathIsNotSeen() {
+    if [[ -n "${ecmHostPathsSeen["$1"]:-}" ]]; then
+        # The path has been seen before.
+        return 1
+    else
+        # The path has not been seen before.
+        # Now it is seen, so record it.
+        ecmHostPathsSeen["$1"]=1
+        return 0
+    fi
 }
 
 ecmHostPathHook() {
-    ecmUnseenHostPath "$1" || return 0
+    ecmHostPathIsNotSeen "$1" || return 0
 
     local xdgConfigDir="$1/etc/xdg"
     if [ -d "$xdgConfigDir" ]