EXPERIMENTAL modify_for_hpux_build.

environment: HP-UX 11.31 ia64, gcc 4.7.1(HP AllianceOne version)

modified 3 files.
- configure.ac - add hpux section.
- crypto/Makefile.am.tpl - add hpux section.
- crypto/compat/arc4random.h - add hpux section.

added 3 files.

- crypto/compat/arc4random_hpux.h - same as arc4random_solaris.h

- crypto/compat/getentropy_hpux.c - based on getentropy_solaris.c
  change including  sys/sha2.h to openssl/sha.h
  remove defining SHA512_...
  remove including link.h, sys/statfs.h, sys/loadavg.h
  remove dl_iterate_phdr() and getloadavg() since hpux doesn't have these system calls.
  this is NOT a good solution and MUST be fixed by using alternate system calls.

- crypto/compat/issetugid_hpux.c - using pstat_getproc() and get*id()
  hpux doesn't have issetugid(), and this is sample implementation.
  it should be verified.