Drop HAVE_ALLOCA_H from os.h since we are not allowed to use alloca() at all.
LUKS: bug fix in valid().
Oracle11: Alignment fix.
hmac-sha-2 formats: Alignment fixes.
Document the OSX krb5-23 problem.
Avoid using GCC-specific pragmas on compilers that don't grok them.
Merge branch 'bleeding-jumbo' into memdbg

* bleeding-jumbo:
  Avoid using GCC-specific pragmas on compilers that don't grok them.
  Document the OSX krb5-23 problem.
  hmac-sha-2 formats: Alignment fixes.
  Oracle11: Alignment fix.
  LUKS: bug fix in valid().
  Drop HAVE_ALLOCA_H from os.h since we are not allowed to use alloca() at all.