message: update mod_pagespeed repo links in .gitmodules
diff: url = https://github.com/google/re2.git
  [submodule "third_party/icu"]
  path = third_party/icu
  - url = https://github.com/pagespeed/icu.git
  + url = https://github.com/apache/incubator-pagespeed-icu.git
  [submodule "third_party/libjpeg_turbo/src"]
  path = third_party/libjpeg_turbo/src
  url = https://chromium.googlesource.com/chromium/deps/libjpeg_turbo
  url = git://git.apache.org/apr.git
  [submodule "third_party/optipng"]
  path = third_party/optipng
  - url = https://github.com/pagespeed/optipng.git
  + url = https://github.com/apache/incubator-pagespeed-optipng.git
  [submodule "third_party/libwebp"]
  path = third_party/libwebp
  url = https://chromium.googlesource.com/webm/libwebp.git
  url = https://boringssl.googlesource.com/boringssl.git
  [submodule "third_party/zlib"]
  path = third_party/zlib
  - url = https://github.com/pagespeed/zlib.git
  + url = https://github.com/apache/incubator-pagespeed-zlib.git
  [submodule "third_party/chromium/src/base"]
  path = third_party/chromium/src/base
  url = https://chromium.googlesource.com/chromium/src/base
  url = https://github.com/google/sparsehash.git
  [submodule "third_party/domain_registry_provider"]
  path = third_party/domain_registry_provider
  - url = https://github.com/pagespeed/domain-registry-provider.git
  + url = https://github.com/apache/incubator-pagespeed-drp.git
  [submodule "third_party/jsoncpp/src"]
  path = third_party/jsoncpp/src
  url = https://github.com/open-source-parsers/jsoncpp.git
  