fix build bug from recent commit:https://github.com/facebook/rocksdb/commit/43c386b72ee834c88a1a22500ce1fc36a8208277
tweak build bug fix
docs for shared library builds
Update README.fb

Update the latest version number.
Simplify build_tools/build_detect_version
update the latest version in README.fb to 2.7
Merge pull request #48 from dyu/master

fix build bug
Add -DROCKSDB_FALLOCATE_PRESENT to fbcode build
moving autovector_test after db_test
Support multi-threaded DisableFileDeletions() and EnableFileDeletions()

Summary:
We don't want two threads to clash if they concurrently call DisableFileDeletions() and EnableFileDeletions(). I'm adding a counter that will enable file deletions only after all DisableFileDeletions() calls have been negated with EnableFileDeletions().

However, we also don't want to break the old behavior, so I added a parameter force to EnableFileDeletions(). If force is true, we will still enable file deletions after every call to EnableFileDeletions(), which is what is happening now.

Test Plan: make check

Reviewers: dhruba, haobo, sanketh

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D14781
Hotfix the bug in table cache's GetSliceForFileNumber

Forgot to fix this problem in master branch. Already fixed it in performance branch.
Automate the preparation step for a new release

Summary: Added a script that prepares the repo for facebook's new rocksdb release, which will automatically do some necessary work to make sure this repo is ready for 3rdparty release.

Test Plan:
Run this script and observed:

* new version was created (both in local and remote repo) as a git tag.
* build_version.cc was updated
* build_detect_platform was changed so that it won't create any new change.

Reviewers: haobo, dhruba, sdong, igor

CC: leveldb

Differential Revision: https://reviews.facebook.net/D15003
Add clang-format rules

Summary:
The rule file is forked from that in Facebook's repo.

I'll add format file for now and team members can tune the rules later.

In this patch, I made only two changes in order to be consistent with existing coding style

`SpacesBeforeTrailingComments: 2`

`ColumnLimit:     80`

Test Plan: N/A

Reviewers: igor

CC: leveldb

Differential Revision: https://reviews.facebook.net/D15015
Merge branch 'master' into performance

Conflicts:
	db/table_cache.cc