Fix configure error for older autoconf

config.m4

@@ -38,7 +38,7 @@ if test "$PHP_FANN" != "no"; then
   PHP_CHECK_LIBRARY($LIBNAME,$LIBSYMBOL,
   [
     PHP_ADD_LIBRARY_WITH_PATH($LIBNAME, $FANN_DIR/$PHP_LIBDIR, FANN_SHARED_LIBADD)
-    AC_CHECK_LIB($LIBNAME,[fann_copy],[ AC_DEFINE(HAVE_FANN_2_2,1,[Fann library version 2.2]) ],[ ], [-lm])
+    AC_CHECK_LIB($LIBNAME,[fann_copy],[ AC_DEFINE(HAVE_FANN_2_2,1,[Fann library version 2.2]) ],[],[-lm])
     AC_DEFINE(HAVE_FANN,1,[Fann library found])
   ],[
     AC_MSG_ERROR([wrong libfann version (you need at least version 2.1) or lib not found])