Completely disable assertions if NDEBUG is set.

Normally, setting NDEBUG disables the assert function call in assert.h.
This is sufficient if we build everything from source. However, as we're
dealing with a number of precompiled binaries, we can also have binaries
which were compiled with NDEBUG not being set. To achieve the same
effect for those binaries (namely: don't make the program crash),
disable the call to abort() inside the assert functions if NDEBUG is
set.

Change-Id: I545927757ae6e972f1567085715d9a6cb6c46107
Merge "Completely disable assertions if NDEBUG is set." into gingerbread