flex: fix WARNING: 'aclocal-1.15' is missing on your system.

- rebuild configurescript

flex.be0

@@ -1,6 +1,6 @@
 #!/usr/bin/env beesh
 
-# BEE_VERSION flex-2.6.4-1
+# BEE_VERSION flex-2.6.4-2
 
 # more info: https://github.com/westes/flex
 # https://www.archlinux.org/packages/core/x86_64/flex/
@@ -22,6 +22,12 @@ PATCHURL+=( "https://beehive.molgen.mpg.de/0a8e8242b37c57b0bc0c6f673bceb5b7/flex
 #    bee_patch "${@}"
 #}
 
+# delivered configure wants aclocal-1.15
+mee_configure_pre() {
+    cd ${S}
+    ./autogen.sh
+}
+
 mee_configure() {
     bee_configure \
     --disable-nls