Require bison 2.7 or newer for regenerating intl/plural.y

The merge of the latest gettext code introduced changes to the yacc
parser source that are incompatible with versions of bison older
than 2.7. Add a configure check for the appropriate versions and
document the requirement in INSTALL.

ChangeLog:

2014-12-22  Will Newton  <will.newton@linaro.org>

	* manual/install.texi: Document that we require bison 2.7
	or above.
	* INSTALL: Regenerate.
	* configure.ac: Use AC_CHECK_PROG_VER instead of
	AC_PATH_PROG when checking for bison and check for
	version 2.7 or above.
	* configure: Regenerate.

1 files changed, 9 insertions, 0 deletions

diff --git a/manual/install.texi b/manual/install.texi
index 2b9b57ca32..d8dc3d58c9 100644
--- a/manual/install.texi
+++ b/manual/install.texi
@@ -449,6 +449,15 @@ GNU @code{gettext} 0.10.36 or later
 @end itemize
 
 @noindent
+If you wish to regenerate the @code{yacc} parser code in the @file{intl}
+subdirectory you will need
+
+@itemize @bullet
+@item
+GNU @code{bison} 2.7 or later
+@end itemize
+
+@noindent
 You may also need these packages if you upgrade your source tree using
 patches, although we try to avoid this.