CMake: don't ignore default UNIX include paths

Previously, this symptom occurred for OpenSSL and was solved
by providing the path to the header files in Homebrew's subdirectory.
This solution is fragile since Homebrew encodes the OpenSSL version
in the path.
Merge pull request #141 from lclc/osxFix

CMake: don't ignore default UNIX include paths on OSX
OTCrypto: don't warn about deprecated functions