[COMMITTED 2.34] intl/plural.y: Avoid conflicting declarations of yyerror and yylex

[arjun.is@lostca.se]

bison-3.8 includes these lines in the generated intl/plural.c:

  #if !defined __gettexterror && !defined YYERROR_IS_DECLARED
  void __gettexterror (struct parse_args *arg, const char *msg);
  #endif
  #if !defined __gettextlex && !defined YYLEX_IS_DECLARED
  int __gettextlex (YYSTYPE *yylvalp, struct parse_args *arg);
  #endif

Those default prototypes provided by bison conflict with the
declarations later on in plural.y.  This patch solves the issue.

Reviewed-by: Arjun Shankar <arjun@redhat.com>
(cherry picked from commit c6d7d6312c21bbcfb236d48bb7c11cedb234389f)
---
 intl/plural.y | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/intl/plural.y b/intl/plural.y
index e02e74541c..2ee128ba01 100644
--- a/intl/plural.y
+++ b/intl/plural.y
@@ -40,6 +40,11 @@
 # define __gettextparse PLURAL_PARSE
 #endif
 
+/* Later we provide those prototypes.  Without these macros, bison may
+   generate its own prototypes with possible conflicts.  */
+#define YYLEX_IS_DECLARED
+#define YYERROR_IS_DECLARED
+
 %}
 %parse-param {struct parse_args *arg}
 %lex-param {struct parse_args *arg}
-- 
2.31.1