Merge branch 'da/darwin' into maint

Newer MacOS X encourages the programs to compile and link with their CommonCrypto, not with OpenSSL. * da/darwin: imap-send: eliminate HMAC deprecation warnings on Mac OS X cache.h: eliminate SHA-1 deprecation warnings on Mac OS X Makefile: add support for Apple CommonCrypto facility Makefile: fix default regex settings on Darwin