Fix update_plugin for OSX (bad sed was used there)

Author: mattam82

template-coq/update_plugin.sh

@@ -1,5 +1,5 @@
-#!/bin/bash
-
+#!/usr/bin/env bash
+SED=`which gsed || which sed`
 TOCOPY="ast_denoter.ml ast_quoter.ml denoter.ml plugin_core.ml plugin_core.mli reification.ml quoter.ml run_extractable.ml run_extractable.mli tm_util.ml"
 
 # Test is gen-src is older than src
@@ -14,7 +14,7 @@ then
     (cd gen-src; ./to-lower.sh)
     rm -f gen-src/*.d
     # Fix an extraction bug: wrong type annotation on eq_equivalence
-    sed -i.bak 's/\r//g' gen-src/cRelationClasses.mli
+    ${SED} -i.bak 's/\r//g' gen-src/cRelationClasses.mli
     patch -N -p0 < extraction.patch
     exit 0
 else