tools: Remove duplicate doxy-filter

This is a duplicate of cpukit/doxy-filter and not used.

tools/build/Makefile.am

@@ -2,6 +2,4 @@ ACLOCAL_AMFLAGS = -I ../../aclocal
 
 bin_SCRIPTS = install-if-change
 
-noinst_SCRIPTS = doxy-filter
-
 include $(top_srcdir)/../../automake/host.am

tools/build/doxy-filter

@@ -1,20 +0,0 @@
-#!/bin/sh
-
-# doxygen input filter
-
-# usage: doxy-filter <input-file-name>
-# Reads <input-file> and writes to stdout.
-
-file=$1
-
-# Does file contain a doxygen @file directive?
-if ! grep -q '@file' $file >/dev/null ; then
-# No, add one
-echo "/** @file $file */"
-cat $file
-else
-# Yes, adjust path to work around doxygen not being able to
-# distinguish file names properly
-exec sed -e "s,@file.*$,@file $file," $file
-fi
-