This incorporates:
2015-06-06 acl-permissions: pacify -Wsuggest-attribute=const
2015-06-05 stdio: Don't redefine gets when using C++
2015-06-05 acl-permissions: port to AIX, C89 HP-UX
2015-06-02 file-has-acl: fix build on Mac OS X 10
2015-06-01 gnulib-tool: concatenate lib_SOURCES to a single line
2015-06-01 pthread_sigmask: discount system version if a simple macro
2015-05-31 readlinkat: avoid OS X 10.10 trailing slash bug
* doc/misc/texinfo.tex, lib/acl-internal.h, lib/get-permissions.c:
* lib/readlinkat.c, lib/set-permissions.c, lib/stdio.in.h:
* m4/acl.m4, m4/pthread_sigmask.m4, m4/readlinkat.m4: Copy from gnulib.
* lib/gnulib.mk: Regenerate.
