make -> gmake typo for freebsd

rebar.config

@@ -20,5 +20,5 @@
    "erlc -I include/erlydtl_preparser.hrl -o test"
    " test/erlydtl_extension_testparser.yrl"},
   {eunit, "make -C $REBAR_DEPS_DIR/merl test"},
-  {"freebsd", eunit, "make -C $REBAR_DEPS_DIR/merl test"}
+  {"freebsd", eunit, "gmake -C $REBAR_DEPS_DIR/merl test"}
  ]}.