update celt version

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@10889 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/mod/codecs/mod_celt/Makefile

 BASE=../../../..
 
-CELT=celt-0.5.0
+CELT=celt-0.5.1
 
 CELT_DIR=$(BASE)/libs/$(CELT)
 LOCAL_CFLAGS=-I$(CELT_DIR)/libcelt