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

configure.ac

@@ -51,7 +51,7 @@ AM_INIT_AUTOMAKE([1.11.1 dist-xz nostdinc
                  m4_bmatch(m4_defn([AC_PACKAGE_VERSION]), [[-_]],
                            [gnu], [gnits]))
 AM_SILENT_RULES([yes])
-AC_CONFIG_HEADERS([lib/config.h:lib/config.hin])
+AC_CONFIG_HEADERS([lib/config.h:lib/config.in.h])
 
 # Checks for the compiler.
 AC_PROG_CC_STDC
@@ -72,7 +72,7 @@ if test "$enable_gcc_warnings" = yes; then
     -Wcast-qual -Wformat -Wpointer-arith -Wwrite-strings'
   warn_c='-Wbad-function-cast -Wmissing-declarations -Wmissing-prototypes
     -Wshadow -Wstrict-prototypes'
-  warn_cxx='-Wnoexcept -Wzero-as-null-pointer-constant'
+  warn_cxx='-Wnoexcept'
   AC_LANG_PUSH([C])
   for i in $warn_common $warn_c;
   do
@@ -89,6 +89,8 @@ if test "$enable_gcc_warnings" = yes; then
   do
     gl_WARN_ADD([$i], [WARN_CXXFLAGS])
   done
+  gl_WARN_ADD([ -Wzero-as-null-pointer-constant], [WARN_CXXFLAGS],
+              [AC_LANG_PROGRAM([], [nullptr])])
   gl_WARN_ADD([-Werror], [WERROR_CXXFLAGS])
   # Warnings for the test suite only.
   gl_WARN_ADD([-Wundef], [WARN_CXXFLAGS_TEST])
@@ -116,9 +118,7 @@ AC_SUBST([YACC_LIBRARY])
 
 # Checks for programs.
 AC_PROG_LEX
-if test "$FLEX" != yes; then
-  AC_MSG_ERROR([Flex is required])
-fi
+$LEX_IS_FLEX || AC_MSG_ERROR([Flex is required])
 AC_PROG_YACC
 AC_PROG_RANLIB
 AC_PROG_GNU_M4