Add [/System]/Library/Frameworks to the Darwin toolchain definition.

According to my Mac, this is the search path:

  Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM 3.5svn)
  Target: x86_64-apple-darwin13.4.0

  #include "..." search starts here:
  #include <...> search starts here:
   /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1
   /usr/local/include
   /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/6.0/include
   /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include
   /usr/include
   /System/Library/Frameworks (framework directory)
   /Library/Frameworks (framework directory)

Fixes bazelbuild#85.

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MOS_MIGRATED_REVID=91194177

Add a visibility predicate to blaze query.

The visible(x, y) query expression computes the subset of nodes in y visible
from all nodes in x.

RELNOTES: Add a visibility predicate to blaze query.

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MOS_MIGRATED_REVID=90765071

Add test dependency

This was making Bazel's bootstrap_test fail.

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MOS_MIGRATED_REVID=90270050

Release notes:

* Lowered requirements from JDK 8 to JDK 7 for Mac users.
* Now an error for a rule to have runtime_deps that are neverlink.
* Allow creating on-the-fly repositories with new_local_repository().
* A (limited) build encyclopedia can be dynamically generated by running
  `bazel build src/main/java:gen_buildencyclopedia`.
* Added a [getting started guide](https://github.com/google/bazel/blob/master/docs/getting-started.md).

Initial release