Merge tag 'v2.5.1_rc2'

Bison 2.5.1_rc2.

* tag 'v2.5.1_rc2': (34 commits)
  Bison 2.5.1_rc2.
  doc: fixes.
  build: fix ChangeLog generation.
  c++: compute the header guards.
  skeletons: remove support for unused directive.
  lalr1.cc: improve Doxygen documentation.
  lalr1.cc: extract stack.hh.
  news: convert to double quotes.
  space changes.
  build: do not prototype flex-generated functions.
  build: fix ChangeLog generation.
  Bison 2.5.1_rc1.
  tests: save/restore Autotest special files when checking XML support.
  tests: AT_SAVE_SPECIAL_FILES / AT_RESTORE_SPECIAL_FILES.
  tests: honor TESTSUITEFLAGS in all the check targets.
  build: do not enable c++ warnings on 0 when nullptr is not supported.
  maint: update gnulib.
  build: config.in.h.
  build: move silent rules.
  glr.c: reduce variable scopes.
  maint: maintainer-release-check.
  maint: shush a syntax-check.
  maint: prefer "commit message" to "log entry".
  command line: fix minor leaks.
  maint: we no longer maintain the ChangeLog.
  maint: fix the generation of the synclines for bison's parser.
  maint: regen.
  maint: import the xmemdup0 gnulib module.
  maint: remove left-over gnulib modules.
  maint: ignore files imported by autopoint.
  build: AC_PROG_LEX: use more readable variable names.
  maint: regen src/parse-gram.[ch]
  maint: simplify parse-gram.y
  maint: s/strncpy/memcpy/, when equivalent

Conflicts:
	Makefile.am
	NEWS
	data/glr.c
	data/lalr1.cc
	data/stack.hh
	examples/rpcalc/local.mk
	src/flex-scanner.h
	src/getargs.c
	src/output.c
	src/parse-gram.c
	src/parse-gram.h
	src/parse-gram.y
	tests/Makefile.am
	tests/bison.in

tests/local.at

@@ -37,6 +37,33 @@ printf "$count\n";' $1], [0], [$3
 ])])
 
 
+# AT_SAVE_SPECIAL_FILES / AT_RESTORE_SPECIAL_FILES
+# ------------------------------------------------
+# Don't interfere with caller's files.
+m4_divert_text([PREPARE_TESTS],
+[at_save_special_files ()
+{
+  for at_save_file in stderr experr expout
+  do
+    test ! -f $at_save_file || mv $at_save_file at-bison-check-$at_save_file.bak
+  done
+}
+
+at_restore_special_files ()
+{
+  for at_save_file in stderr experr expout
+  do
+    test ! -f at-bison-check-$at_save_file.bak ||
+      mv at-bison-check-$at_save_file.bak $at_save_file
+  done
+}
+])
+
+m4_define([AT_SAVE_SPECIAL_FILES],    [at_save_special_files])
+m4_define([AT_RESTORE_SPECIAL_FILES], [at_restore_special_files])
+
+
+
 ## ------------------------------- ##
 ## Macros decoding Bison options.  ##
 ## ------------------------------- ##
@@ -288,10 +315,7 @@ m4_if(m4_bregexp([$4], [: warning: ]), [-1], [],
         # are added after the grammar file name, so skip these checks
         # in that case.
         if test -z "${POSIXLY_CORRECT+set}"; then
-          # Don't interfere with caller's files.
-          if test -f stderr; then mv stderr at-bison-check-stderr.bak; fi
-          if test -f experr; then mv experr at-bison-check-experr.bak; fi
-          if test -f expout; then mv expout at-bison-check-expout.bak; fi
+          ]AT_SAVE_SPECIAL_FILES[
 
           # To avoid expanding it repeatedly, store specified stdout.
           ]AT_DATA([expout], [$3])[
@@ -343,16 +367,7 @@ m4_if(m4_bregexp([$4], [: warning: ]), [-1], [],
           ]AT_CHECK(AT_QUELL_VALGRIND[[ bison ]$1[ --warnings=none \
                     -Werror]], [[0]], [expout])[
 
-          # Restore caller's files.
-          if test -f at-bison-check-expout.bak; then
-            mv at-bison-check-expout.bak expout
-          fi
-          if test -f at-bison-check-experr.bak; then
-            mv at-bison-check-experr.bak experr
-          fi
-          if test -f at-bison-check-stderr.bak; then
-            mv at-bison-check-stderr.bak stderr
-          fi
+          ]AT_RESTORE_SPECIAL_FILES[
         fi
       ]])
 ])
@@ -363,8 +378,9 @@ m4_if(m4_bregexp([$4], [: warning: ]), [-1], [],
 # defined.  It doesn't make sense to invoke this macro if Bison is expected to
 # have a non-zero exit status.
 m4_define([AT_BISON_CHECK_XML],
-[[if test x"$BISON_TEST_XML" = x1 && test x"$XSLTPROC" != x""; then
-  mkdir xml-tests]
+[[if test x"$BISON_TEST_XML" = x1 && test x"$XSLTPROC" != x""; then]
+  AT_SAVE_SPECIAL_FILES
+  [mkdir xml-tests]
   m4_pushdef([AT_BISON_ARGS],
              [m4_bpatsubsts([[$1]],
                             [--report(-file)?=[^][ ]*], [],
@@ -386,8 +402,9 @@ m4_define([AT_BISON_CHECK_XML],
   AT_CHECK([[$XSLTPROC \
              `]]AT_QUELL_VALGRIND[[ bison --print-datadir`/xslt/xml2dot.xsl \
              xml-tests/test.xml]], [[0]], [expout])
-  [rm -rf xml-tests expout
-fi]])
+  [rm -rf xml-tests expout]
+  AT_RESTORE_SPECIAL_FILES
+[fi]])
 
 # AT_QUELL_VALGRIND
 # -----------------