release script: Improve override for libtoolize.

scripts/reconfigure

@@ -43,17 +43,19 @@ set -e
 # this should guarantee reproducible results from automake runs
 export PERL_HASH_SEED=0
 
-case $(uname -s) in
-  Darwin)
-    libtoolize=glibtoolize
-    if [[ -z "${SED+set}" ]] && command -v gsed >/dev/null; then
-      SED=gsed
-    fi
-    ;;
-  *)
-    libtoolize=libtoolize
-    ;;
-esac
+if [[ -z "${libtoolize:-}" ]]; then
+  case $(uname -s) in
+    Darwin)
+      libtoolize=glibtoolize
+      if [[ -z "${SED+set}" ]] && command -v gsed >/dev/null; then
+        SED=gsed
+      fi
+      ;;
+    *)
+      libtoolize=libtoolize
+      ;;
+  esac
+fi
 
 SED=${SED-sed}
 if sed_version=$($SED --version 2>/dev/null) && [[ $sed_version = *GNU\ sed* ]]; then
@@ -70,9 +72,8 @@ fi
 
 autoreconf -i --force
 $libtoolize --force --copy
-#todo: escape / in $libtoolize
 libtoolversion=$($libtoolize --version \
-                      | ${SED} -e 's/^'"$libtoolize"' \(([^)]*) \)\{0,1\}\([0-9.]*\)/\2/;q')
+                      | ${SED} -e 's/^'"${libtoolize##*/}"' \(([^)]*) \)\{0,1\}\([0-9.]*\)/\2/;q')
 declare -a patches
 case "$libtoolversion" in
   (2.4.6)