libjson-c: also install .pc file for compatibility libjson

Older packages, which did not follow the renaming yet, do not
find the library otherwise via pkgconfig.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

SVN-Revision: 39228

package/libs/libjson-c/Makefile

 #
-# Copyright (C) 2006-2010 OpenWrt.org
+# Copyright (C) 2006-2014 OpenWrt.org
 #
 # This is free software, licensed under the GNU General Public License v2.
 # See /LICENSE for more information.
@@ -61,6 +61,7 @@ define Build/InstallDev
 	$(CP) $(PKG_INSTALL_DIR)/usr/lib/libjson-c.{a,so*} $(1)/usr/lib/
 	$(INSTALL_DIR) $(1)/usr/lib/pkgconfig
 	$(CP) $(PKG_INSTALL_DIR)/usr/lib/pkgconfig/json-c.pc $(1)/usr/lib/pkgconfig/
+	$(CP) $(PKG_INSTALL_DIR)/usr/lib/pkgconfig/json.pc $(1)/usr/lib/pkgconfig/
 endef
 
 define Package/libjson-c/install