Summary:
Added new target ##make analyze## into Makefile. This command runs clang static analyzer and builds the sources as ##make all##. The result report is put into ##$(RocksDbSourceRoot)/can_build_report/##

If the development environment is a Facebook devserver and ##ROCKSDB_NO_FBCODE## is not set, then scan-build is used from fbcode. If it is run not on a Facebook devserver, scan-build should be available in ##$PATH##. I'll add details to wiki how to install scan-build on a non Facebook devserver environment.

Test Plan:
Run the fallowing commands on a Facebook devserver and Mac OS, and ensure no build or test errors.

```
% make all check -j32
% make clean
% USE_CLANG=1 make all -j32
% make analyze
% USE_CLANG=1 make analyze
```

Reviewers: sdong, lgalanis, leveldb, igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D32799