- move srtp to libsrtp, rename package from srtp to libsrtp
- use CONIGURE_ARGS instead of overriding Build/Configure
- use PKG_INSTALL instead of overriding Build/Compile
- refresh patches
git-svn-id: svn://svn.openwrt.org/openwrt/packages@29808 3c298f89-4303-0410-b956-a3cf2f4a3e73