We don't globally define NDEBUG in the tree because we use our own macros to detect optimization or debugging.

Other libraries in third_party do reference NDEBUG in various ways, and expect it to be set correctly.

In particular, the following libraries make some sort of reference to NDEBUG:

• boost-1.56
• gperftools-2.2
• pcre-8.30
• s2
• snappy-1.1.2
• v8

We should enable NDEBUG for all of third party when appropriate. This most likely corresponds to the configuration where we are building with optimization on, and debugging off.