build: Fix out-of-source-tree installation of libguile-2.0-gdb.scm.

* libguile/Makefile.am (install-data-local): Use $< instead of just
  libguile-2.0-gdb.scm.  Quote file names in $(INSTALL_DATA) invocation.
Fix typo in manual.

* doc/ref/api-foreign.texi (Void Pointers and Byte Access):
  (rnrs bytevector) --> (rnrs bytevectors).
Import Gnulib modules: link, fsync, readlink, rename, mkdir, rmdir, unistd.

* lib/fsync.c:
* lib/link.c:
* lib/mkdir.c:
* lib/strdup.c:
* m4/fsync.m4:
* m4/link.m4:
* m4/mkdir.m4:
* m4/strdup.m4: New files.

* lib/Makefile.am
* m4/gnulib-cache.m4
* m4/gnulib-comp.m4: Add modules.
Rely on Gnulib for fsync, link, readlink, mkdir, rmdir, and rename.

* libguile/filesys.c: Remove 'fsync' wrapper for MinGW.
  (scm_link, scm_readlink, scm_mkdir, scm_rmdir): Define these
  unconditionally.
  (my_rename): Remove.
  (scm_rename): Use 'rename' instead of 'my_rename'.
Rely on Gnulib for <unistd.h>.

* libguile/async.c:
* libguile/backtrace.c:
* libguile/error.c:
* libguile/filesys.c:
* libguile/fports.c:
* libguile/gc-malloc.c:
* libguile/gc.c:
* libguile/gdbint.c:
* libguile/init.c:
* libguile/ioext.c:
* libguile/load.c:
* libguile/mallocs.c:
* libguile/mkstemp.c:
* libguile/ports.c:
* libguile/posix.c:
* libguile/r6rs-ports.c:
* libguile/random.c:
* libguile/rw.c:
* libguile/scmsigs.c:
* libguile/script.c:
* libguile/simpos.c:
* libguile/socket.c:
* libguile/stime.c:
* libguile/strports.c:
* libguile/threads.c: Unconditionally include <unistd.h>.
SRFI-18: Export 'current-thread'.

Fixes <http://debbugs.gnu.org/16890>.
Reported by Xin Wang <dram.wang@gmail.com>.

* module/srfi/srfi-18.scm: Reexport 'current-thread'.
* THANKS: Add "Xin Wang" to fixes section.
build: Make c-tokenize.c build on non-GNU systems.

* libguile/c-tokenize.lex: Add %top directive to include <config.h>
  first.  This fixes builds on systems that use Gnulib's <stdio.h> and
  similar replacements.  See <http://hydra.nixos.org/build/9259627> for
  an example.
Add missing files to the test-suite Makefile.

* test-suite/Makefile.am (SCM_TESTS): Add "tests/compiler.test",
  "tests/encoding-escapes.test", "tests/encoding-iso88591.test",
  "tests/encoding-iso88597.test", "tests/encoding-utf8.test",
  "tests/pairs.test", "tests/records.test", "tests/sort.test",
  "tests/srfi-17.test", "tests/srfi-18.test", "tests/srfi-98.test",
  "tests/streams.test", "tests/vectors.test", and "tests/web-client.test".
SRFI-19: Update the table of leap seconds.

* module/srfi/srfi-19.scm (leap-second-table): Update to include the two
  most recent leap seconds.