Replace RE2 import with a dependency

third_party/re2/testinstall.cc

-// Copyright 2008 The RE2 Authors.  All Rights Reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-#include <re2/re2.h>
-#include <re2/filtered_re2.h>
-#include <stdio.h>
-
-using namespace re2;
-
-int main(void) {
-        FilteredRE2 f;
-        int id;
-        f.Add("a.*b.*c", RE2::DefaultOptions, &id);
-        vector<string> v;
-        f.Compile(&v);
-        vector<int> ids;
-        f.FirstMatch("abbccc", ids);
-
-        if(RE2::FullMatch("axbyc", "a.*b.*c")) {
-                printf("PASS\n");
-                return 0;
-        }
-        printf("FAIL\n");
-        return 2;
-}