Log Message:
Update "apr" package to version 1.5.1. Changes since 1.5.0:
- apr_os_proc_mutex_get() on Unix:  Avoid segfault for cross-
  process pthread mutexes.  [Yann Ylavic <ylavic.dev gmail.com>]
- When using shmget-based shared memory, the ID used for ftok is
  now an APR hash of the filename instead of the constant '1'.
  We do this to help avoid collisions. Bug 53996 [Jim Jagielski]
- apr_socket_atreadeof(): Fix breakage on OS X. [Jim Jagielski]
- Fix POSIX shared memory (shm_open) use for named shared memory.
  Includes adding '--enable-posix-shm' to force POSIX shm if
  available, and OS X compatibility. Bug 55928.
  [Jozef Hatala <jh-asf skrt org>, Jim Jagielski]
- Fix apr_escape.c compilation errors on EBCDIC platforms.
  [Eric Covener]
- FreeBSD 10: Correct a regression in 1.5.0 which affected non-
  blocking sockets in some applications, including httpd.  [Jeff
  Trawick]
- apr_skiplist: Add compatibility with C++ applications.
  [Jeff Trawick]
- Correct a regression in 1.5.0 which affected out-of-tree
  builds on Unix.  [Rainer Jung]
- Improve platform detection for bundled expat by updating
  config.guess and config.sub. [Rainer Jung]