OpenSSL is 'deprecated' instead of OSX's CryptoAPI; it still works fine thus ignore the deprecation warning when compiling with llvm (XCode)

src/proxy-bio.c:275:7: warning: 'BIO_write' is deprecated [-Wdeprecated-declarations]
  r = BIO_write(b->next_bio, buf, strlen(buf));
      ^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/openssl/bio.h:587:5: note: 'BIO_write'
      declared here
int     BIO_write(BIO *b, const void *data, int len) DEPRECATED_IN_MAC_OS_X_VERSION_10_7_AND_LATER;
        ^