Apple Mac OS X Keychain support (2/3)
 - cleaned up, formatted according to style of rest of source tree and merged past patch by Brian Raderman <brian@irregularexpression.org> into macosx.[ch]
 - reformatted cryptoapi.c to match rest of tree while I was at it
 - this is slice 2 of 3: fully functional but using the deprecated CSSM API for accessing the certificates and doing the signature