Fix pkg-config file syntax

ChangeLog

@@ -1,3 +1,6 @@
+2010-04-25 Julien Blache <jb@jblache.org>
+	* tools/sane-backends.pc.in: syntax fixes.
+
 2010-04-25 m. allan noah <kitno455 at gmail dot com>
 	* ChangeLog-1.0.21, Makefile.in: ChangeLog for 1.0.21 release
 	* configure, configure.in: version 1.0.22git

tools/sane-backends.pc.in

@@ -9,6 +9,6 @@ Name: SANE Backends
 Description: Backends for SANE, the universal scanner interface
 Version: @VERSION@
 Requires:
-Libs: -L$(libdir) -lsane
-Libs.private: $(ldflags) $(libs)
-Cflags: -I$(includedir)
+Libs: -L${libdir} -lsane
+Libs.private: ${ldflags} ${libs}
+Cflags: -I${includedir}