gnulib: sync from latest gnulib, notably bootstrap and parse-datetime

* bootstrap: Sync from gnulib.
* doc/.gitignore: Rename getdate.texi to parse-datetime.texi.
* doc/Makefile.am (tar_TEXINFOS): Likewise.
* doc/tar.texi (Top): Adjust to renaming of getdate to parse-datetime.
* gnulib.modules: Likewise.  Also, remove ftruncate (now obsolete).
And add inttostr (we missed this dependency).
* src/tar.c: Include parse-datetime.h, not getdate.h.  All calls
to get_date replaced with parse_datetime.

doc/.gitignore

@@ -1,7 +1,7 @@
 genfile.texi
-getdate.texi
 header.texi
 manual
+parse-datetime.texi
 stamp-vti
 tar.aux
 tar.cp

doc/Makefile.am

@@ -24,9 +24,9 @@ tar_TEXINFOS = \
  fdl.texi\
  freemanuals.texi\
  genfile.texi\
- getdate.texi\
  header.texi\
  intern.texi\
+ parse-datetime.texi\
  rendition.texi\
  snapshot.texi\
  sparse.texi\

doc/tar.texi

@@ -318,7 +318,7 @@ Date input formats
 * Pure numbers in date strings::   19931219, 1440.
 * Seconds since the Epoch::        @@1078100502.
 * Specifying time zone rules::     TZ="America/New_York", TZ="UTC0".
-* Authors of get_date::            Bellovin, Eggert, Salz, Berets, et al.
+* Authors of parse_datetime::      Bellovin, Eggert, Salz, Berets, et al.
 
 Controlling the Archive Format
 
@@ -8560,7 +8560,7 @@ $ @kbd{tar -c -f archive.tar -C / home}
 @xref{Integrity}, for some of the security-related implications
 of using this option.
 
-@include getdate.texi
+@include parse-datetime.texi
 
 @node Formats
 @chapter Controlling the Archive Format