Fix a missing-initializer warning
Fix four unused-value warnings
Make scrypt_ensure_zero static

As an alternative, it should get a function prototype.
Fix the name of scrypt_to_set_fatal_error to match one in header
Remove include <malloc.h>, which OSX doesn't have.

I'll see what needs it soon.
Fix warning about missing attribute((noreturn))
Fix "function declaration is not a prototype" warnings
Avoid a GCC 4.7 implicit conversion warning.
Merge pull request #9 from nmathewson/gcc_warnings

Fix some not-always-turned-on compiler warnings