maint: use getentropy and new tempname modules

maint: use getentropy and new tempname modules

Update gnulib submodule to latest and use its new features.
Gnulib’s new getentropy module means coreutils can now assume
getentropy instead of approximating it, badly in some cases.
Gnulib’s improvements to the tempname module mean coreutils no
longer needs to maintain private patches.
* bootstrap.conf (gnulib_modules): Remove gettimeofday.
* gl/lib/randread.c (NAME_OF_NONCE_DEVICE): Remove.
(get_nonce): Return success indicator.  Remove bytes_bound arg.
All callers changed.  Rewrite by using getentropy instead of
reading the nonce device and falling back on gettimeofday.
Fail if getentropy fails.
(randread_new): Return NULL (setting errno) if get_nonce fails.
All callers changed.
* gl/lib/tempname.c.diff, gl/lib/tempname.h.diff:
* gl/modules/tempname.diff: Remove.
* gl/modules/randread (Depends-on):
Depend on getentropy, not gettimeofday.
* src/ptx.c (swallow_file_in_memory):
* src/shuf.c (read_input):
Adjust to read_file changes in Gnulib.
* src/shred.c (main):
* src/shuf.c (main):
* src/sort.c (random_md5_state_init):
Diagnose the new form of randread_new failures: randread_new can
fail now when !random_source, meaning getentropy failed.