Nicked from http://cvs.fedoraproject.org/viewvc/devel/xdelta/xdelta-1.1.3-pkgconfig.patch

--- /dev/null	2006-05-17 14:47:01.398050000 +0200
+++ xdelta-1.1.3/xdelta.pc.in	2006-05-30 16:00:55.000000000 +0200
@@ -0,0 +1,13 @@
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+libdir=@libdir@
+includedir=@includedir@
+pkgdatadir=@pkgdatadir@
+
+Name: xdelta
+Description: A binary file delta generator and an RCS replacement library.
+Version: @VERSION@
+Requires: glib-2.0
+Libs: -L${libdir} -lxdelta -ledsio
+Cflags: -I${includedir}
+
--- /dev/null	2006-05-17 14:47:01.398050000 +0200
+++ xdelta-1.1.3/xdelta-config	2006-05-30 16:04:22.000000000 +0200
@@ -0,0 +1,60 @@
+#!/bin/bash
+#
+# Simple wrapper around pkg-config to replace /usr/bin/<foo>-config scripts
+# 
+# Copyright 2006 Red Hat, Inc.  
+# Jeremy Katz <katzj@redhat.com>
+
+CFGPATH=$(basename $0)
+MODULE=${CFGPATH%-config}
+
+usage() {
+    pkg-config --help
+    exit 1
+}
+
+if [ $# -lt 1 ]; then
+    usage 1>&2
+fi
+
+ARGS=""
+
+while test $# -gt 0; do
+  case $1 in 
+      --version)
+	  ARGS="$ARGS --modversion"
+	  ;;
+      --cflags)
+	  ARGS="$ARGS --cflags"
+	  ;;
+      --libs)
+	  ARGS="$ARGS --libs"
+	  ;;
+      --libdir*)
+	  ARGS="$ARGS --libs-only-L"
+	  ;;
+      --includedir*)
+	  ARGS="$ARGS --cflags-only-I"
+	  ;;
+      --prefix*)
+          ARGS="$ARGS --variable=prefix"
+          ;;
+      --exec-prefix*)
+          ARGS="$ARGS --variable=exec_prefix"
+          ;;
+      --module*)
+	  if echo $1 | grep -q '=' ; then
+	      MODULE=`echo $1 | sed 's/^--module=//'`
+	  else
+	      MODULE=$2
+	      shift
+	  fi
+	  ;;
+      *)
+	  usage 1>&2
+	  ;;
+  esac
+  shift
+done
+
+pkg-config $ARGS $MODULE
--- xdelta-1.1.3/Makefile.am.pkgconfig	2006-05-30 16:00:55.000000000 +0200
+++ xdelta-1.1.3/Makefile.am	2006-05-30 16:00:55.000000000 +0200
@@ -27,6 +27,9 @@
 m4datadir = $(datadir)/aclocal
 m4data_DATA = xdelta.m4
 
+pkgconfigdir = $(libdir)/pkgconfig
+pkgconfig_DATA = xdelta.pc
+
 ## $Format: "libxdelta_la_LDFLAGS = -version-info $LibCurrent$:$LibRevision$:$LibAge$" $
 libxdelta_la_LDFLAGS = -version-info 2:0:0
 
--- xdelta-1.1.3/configure.in.pkgconfig	2006-05-30 16:00:55.000000000 +0200
+++ xdelta-1.1.3/configure.in	2006-05-30 16:00:55.000000000 +0200
@@ -63,6 +63,8 @@
 AC_HEADER_STDC
 AC_PROG_MAKE_SET
 
+PKG_PROG_PKG_CONFIG
+
 AC_CHECK_FUNCS(gettimeofday)
 AC_HEADER_TIME
 
@@ -83,7 +85,7 @@
 	  doc/Makefile
           test/Makefile
           djgpp/Makefile
-	  xdelta-config
+	  xdelta.pc
 	  libedsio/Makefile
 	  libedsio/edsio-comp,