[glibc] intl: Fix clang -Wunused-but-set-variable on plural.c

[glibc] intl: Fix clang -Wunused-but-set-variable on plural.c

[Adhemerval Zanella]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=6ee5a9767a245455720d39eeaa3ce136825e8a42

commit 6ee5a9767a245455720d39eeaa3ce136825e8a42
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Wed Aug 24 11:13:23 2022 -0300

    intl: Fix clang -Wunused-but-set-variable on plural.c
    
    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>

Diff:
---
 intl/Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/intl/Makefile b/intl/Makefile
index 315c75a18f..1c3b2a2273 100644
--- a/intl/Makefile
+++ b/intl/Makefile
@@ -154,7 +154,8 @@ $(objpfx)tst-gettext5.out: $(objpfx)tst-gettext.out
 $(objpfx)tst-gettext6.out: $(objpfx)tst-gettext.out
 
 CPPFLAGS += -D'LOCALEDIR="$(localedir)"' \
-	    -D'LOCALE_ALIAS_PATH="$(localedir)"'
+	    -D'LOCALE_ALIAS_PATH="$(localedir)"' \
+	    -Wno-unused-but-set-variable
 BISONFLAGS = --yacc --no-lines --name-prefix=__gettext --output
 
 $(inst_localedir)/locale.alias: locale.alias $(+force)