Turn -Wshadow back on

Summary: It turns out that -Wshadow has different rules for gcc than clang. Previous commit fixed clang. This commits fixes the rest of the warnings for gcc.

Test Plan: compiles

Reviewers: ljin, yhchiang, rven, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D28131
Turn off -Wshadow

Summary:
So glibc is not -Wshadow-safe, so we need to turn it off :(

      error: ‘int sigaction(int, const sigaction*, sigaction*)’ hides
      constructor for ‘struct sigaction’

The rest of the changes in this diff is that we include .h files under rocksdb namespace, which is a no-no.

Test Plan: compiles now

Reviewers: ljin, yhchiang, rven, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D28413
Turn on -Wshadow for travis
Make PartialCompactionFailure Test more robust.

Summary: Make PartialCompactionFailure Test more robust.

Test Plan:
export ROCKSDB_TESTS=PartialCompactionFailure
./db_test

Reviewers: ljin, sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D28425
[RocksJava] -WShadow improvements

Minor corrections to resolve -WShadow build problems with RocksJava code.
Merge pull request #387 from fyrz/RocksJava-WShadow-Fix

[RocksJava] -WShadow improvements
make DropWritesFlush deterministic

Summary:
TEST_WaitForFlush should wait until it sees error when parameter is set
to true so we don't need to loop and timeout

Test Plan: ROCKSDB_TESTS=DropWritesFlush ./db_test

Reviewers: sdong, igor

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D28419
Make PartialCompactionFailure Test more robust again.

Summary:
Make PartialCompactionFailure Test more robust again by
blocking background compaction until we simulate the
file creation error.

Test Plan:
export ROCKSDB_TESTS=PartialCompactionFailure
./db_test

Reviewers: sdong, igor, ljin

Reviewed By: ljin

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D28431