Remove un-needed AC_SUBST() for OpenAL (PKG_CHECK_MODULES does this).

Originally committed to SVN as r1954.

configure.in

@@ -194,8 +194,8 @@ if test "$with_openal" = "yes"; then
   AC_DEFINE(WITH_OPENAL, 1, [Enable OpenAL support])
 fi
 
-AC_SUBST(OPENAL_CFLAGS)
-AC_SUBST(OPENAL_LIBS)
+
+
 
 #################
 # Video Providers