Clang warns that '__gettextnerrs' set but not used:
intl/plural.c:1034:9: error: variable '__gettextnerrs' set but not used
[-Werror,-Wunused-but-set-variable]
int yynerrs = 0;
^
Clang 15 (https://reviews.llvm.org/D122271) -Wunused-but-set-variable
gives a warning while GCC doesn't. The -Wunused-but-set-variable is
available in GCC 4.6, lower than the minimum required version 6.2.
Since the file is auto-generated, suppress the warning with a compiler
flag.
Reviewed-by: Fangrui Song <maskray@google.com>
