Fix eclipse build

Summary:
D1368543 but forgot to add it to the .classpath file, which causes
eclipse builds to fail.

Test Plan: Built buck in eclipse
Make `getInputsToCompareToOutput` return `ImmutableCollection`

Summary:
In line with D1361352 and D1362050, this makes the return type
of ##getInputsToCompareToOutput## immutable.  In almost all cases,
we return immutable collections from this function anyway, and this
cleans up a case that could generate lint warnings.

Test Plan: ant test
Actually use test-selectors with --dry-run

Summary:
`buck test ... --dry-run` shows two things: the targets that match your
command-line options; and, where supported, the individual tests that
match your command-line options.  However, this wasn't working properly
with `--filter`:

This fixes buck to use the same test-selectors logic it uses when not
doing a dry-run: if you are using selectors then don't show
`ResultsAvailable` events where there are no actual test results.

The context here is this was causing a bug in testpilot.  When
test-pilot does a dry-run, with the `--buck-args` you told it to run
buck with, it was listing more tests than expected (in this example,
`com.example.TestA#test2`, `com.example.TestB#test2`, and
`com.example.TestC#test2`):

  $ t --buck-args \\--filter \#testFoo
  buck-cli: exec: 'buck' 'test' ... '--all' '--dry-run' '--filter' '#test2'

Fixing dry-run to work with test-selectors / filtering should unbreak
this test-pilot bug.

Test Plan:
```
lang=none, name=Before
& buck test test/com/facebook/buck/graph/ --dry-run --filter Dot
...
DRYRUN <100ms  5 Passed   0 Skipped   0 Failed   com.facebook.buck.graph.AbstractAcyclicDepthFirstPostOrderTraversalTest
DRYRUN <100ms  2 Passed   0 Skipped   0 Failed   com.facebook.buck.graph.AbstractBottomUpTraversalTest
DRYRUN <100ms  1 Passed   0 Skipped   0 Failed   com.facebook.buck.graph.DotTest
DRYRUN <100ms  1 Passed   0 Skipped   0 Failed   com.facebook.buck.graph.HashMultimapTest
DRYRUN <100ms  7 Passed   0 Skipped   0 Failed   com.facebook.buck.graph.MutableDirectedGraphTest
```

```
lang=none, name=After
& buck test test/com/facebook/buck/graph/ --dry-run --filter Dot
...
DRYRUN <100ms  1 Passed   0 Skipped   0 Failed   com.facebook.buck.graph.DotTest
```
Update nailgun to fix race.

Summary:
Update nailgun to https://github.com/martylamb/nailgun at
commit df35649c56b793f9a37e6beb02b0d0dee57b4fda to fix a potential
race condition where client disconnection handling would only be
triggered if the handler was installed before the disconnection
occured.

Test Plan: buck test --all