Baseline: f3ae88ee043846e7acdffd645137075a4e72c573

Cherry picks:
   + c58ba098526b748f9c73e6229cafd74748205aa1:
     Release to GCS: put the final release in its own directory
   + 0acead4ea3631240659836ce6ecd6d7f67fd352b:
     Update protobuf to latest master at a64497c and apply
     @laszlocsomor's latest changes from
     https://github.com/google/protobuf/pull/2969 on top of it.
   + d0242ce4a87929f2528f4602d0fb09d1ccfcea94:
     Make symlinks consistent
   + d953ca8b87a46decbce385cebb446ae0dd390881:
     Clean VanillaJavaBuilder output directories
   + 755669fb5de1f4e762f27c19776cac9f410fcb94:
     Pass all the environment variable to Bazel during bootstrapping
   + 6f041661ca159903691fcb443d86dc7b6454253d:
     Do not mark the JDK7 installer -without-jdk-installer
   + 720561113bfa702acfc2ca24ce3cc3fd7ee9c115:
     Fix #2958: Installer should not overwrite bazelrc
   + 511c35b46cead500d4e76706e0a709e50995ceba:
     Bootstrap: move the fail function to the top
   + 8470be1122825aae8ad0903dd1e1e2a90cce47d2:
     Clean up javac and Error Prone targets
   + 4a404de2c6c38735167e17ab41be45ef6fc4713a:
     Update javac version to 9-dev-r4023-2
   + 36ce4b433e19498a78c34540d5a166d4e0006b22:
     Update javac version to 9-dev-r4023-2
   + 38949b8526bdb3e6db22f3846aac87162c28c33f:
     Migrate off versioned javac and Error Prone targets
   + 1a57d298f8aa6ea8136d93223902104f2479cd2a:
     Re-enabling passing -sourcepath via javacopts.
   + eb565f408e03125e92d42b00756e519795be6593:
     Make make sure that msys build actually builds msys version
   + 39f328cf392056618d1a3ead4835a138b189a06d:
     Fix typo. Also do not override host_cpu for msvc.
   + 624802893f4fe72118f00a78452605d41a2e1c6f:
     Select correct JDK for windows_msys
   + c4f271d1a68366b6fa5ff38ea7d951b6a22af044:
     Automated g4 rollback of commit
     3e5edafa2a04a71cd3596e929e83222da725f3f9.
   + 926180997a0f296a5a009326aead887279ce0a90:
     Remove process-tools.cc which I forgot to delete during the last
     rollback.
   + baca6e4cb023649920871b74810927d304729e59:
     Fix #2982: Bazel installer should not check for installed JDK if
     using a bundled JDK.
   + 866ecc8c3d5e0b899e3f0c9c6b2265f16daae842:
     Disable msys path conversion on Windows.
   + cc21998c299b4d1f97df37b961552ff8168da17f:
     Rollforward #2 of: Basic open-source crosstool to support
     targeting apple platform types.
   + 0f0ccc4fc8229c1860a9c9b58089d6cfb2ee971f:
     Escape % in strings that will appear in Crosstool
   + 3b08f774e7938928e3a240a47a0a7554cdc8d50b:
     Adding feature for linking C Run-Time library on Windows
   + 3566474202d1978acfdcb7e5ff73ee03ea6f3df9:
     Do not use sed -E in bootstrap/compile.sh
   + c3cf7d917afd02d71de3800cd46ad8d14f1ddf55:
     Reverts non-xcode-available darwin crosstool generation.

Important changes:

  - Fixes regression in 0.5.0 requiring Xcode to build C++ on OSX.