Fix %error-verbose for conflicts resolved by %nonassoc.

Fix %error-verbose for conflicts resolved by %nonassoc.

* NEWS (2.5): Document.
* data/glr.c (yyreportSyntaxError): Fix this by checking
yyis_table_ninf.
* data/yacc.c (yysyntax_error): Likewise.
* data/lalr1.cc (yysyntax_error_): Fix this by checking
yytable_ninf_.
* data/lalr1.java (yysyntax_error): Likewise.
* tests/conflicts.at (%nonassoc and eof): Update expected output
and remove FIXME.
(cherry picked from commit 53f036ce027289d3f5e70c88735b88aa6725381d)

Conflicts:

	data/lalr1.cc
	data/lalr1.java
	src/parse-gram.c
	src/parse-gram.h