check for 'ilbc2' pkg-config name first so we canuse overriden centos package

configure.ac

@@ -1333,9 +1333,11 @@ PKG_CHECK_MODULES([BROADVOICE], [broadvoice >= 0.1.0],[
   AM_CONDITIONAL([HAVE_BROADVOICE],[true])],[
   AC_MSG_RESULT([no]); AM_CONDITIONAL([HAVE_BROADVOICE],[false])])
 
-PKG_CHECK_MODULES([ILBC], [ilbc >= 0.0.1],[
+PKG_CHECK_MODULES([ILBC], [ilbc2 >= 0.0.1],[
   AM_CONDITIONAL([HAVE_ILBC],[true])],[
-  AC_MSG_RESULT([no]); AM_CONDITIONAL([HAVE_ILBC],[false])])
+    PKG_CHECK_MODULES([ILBC], [ilbc >= 0.0.1],[
+      AM_CONDITIONAL([HAVE_ILBC],[true])],[
+      AC_MSG_RESULT([no]); AM_CONDITIONAL([HAVE_ILBC],[false])])])
 
 PKG_CHECK_MODULES([G7221], [g722_1 >= 0.2.0],[
   AM_CONDITIONAL([HAVE_G7221],[true])],[