folly: avoid used-uninitialized bug in a test

Summary:
Clang complained about this.
* folly/gen/test/FileBenchmark.cpp (BENCHMARK): Initialize "rfd" to -1
and verify that it is set to something nonnegative in the first
BENCHMARK_SUSPEND block.

Test Plan:
Run this:
fbconfig -r --clang --with-project-version clang:dev folly/gen && fbmake runtests
and observe that compilation now succeeds. (and test results remain unchanged)

Reviewed By: tudorb@fb.com

Subscribers: njormrod

FB internal diff: D1551180

Tasks: 4090011
Make TSocketAddress use folly::IPAddress

Summary:
Step 1 of moving TAsyncSocket and friends to folly.

folly::IPAddress changes (can split these off if requested):
* isLoopback looks for a single address, as opposed to subnet
* For V6, isPrivate & isLoopback don't seem to check mapped addresses

TSocketAddress changes:
* Make union use folly::IPAddress instead of sockaddr struct.  external_ bool to tell if using AF_UNIX instead.
* manage the port and scope/zone info ourselves

@override-unit-failures

Overriding failures, can't get contbuild to finish all builds after several tries.  None of the failures look related

Test Plan:
fbconfig -r thrift
fbmake runtests
fbconfig folly/test:network_address_test
fbmake runtests

Reviewed By: simpkins@fb.com

Subscribers: snaptu-diffs@, trunkagent, hphp-diffs@, njormrod, fbcode-common-diffs@, doug, ruibalp, ps, alandau, bmatheny

FB internal diff: D1479365

Tasks: 3658665
equality for exception_wrapper

Summary:
std::exception_ptr expose methods to compare equality and it
will be great to do so for folly::exception_wrapper (it helps in gmock
testing).

Test Plan: added some unit tests to test this new functionality

Reviewed By: mhorowitz@fb.com

Subscribers: njormrod

FB internal diff: D1546597
Add non-strict mode to folly::Singleton

Summary:
It is difficult to guarantee every binary can call
registrationComplete; for now, support a mode where we don't enforce the
strict registration lifecycle.  In the fullness of time, we can make
strictness the default.

Test Plan: runtests

Reviewed By: lins@fb.com

Subscribers: lins, anca, njormrod

FB internal diff: D1551688
Bump version to 6:0