[glibc] Simplify tzdb-related configuration

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=d420b69b8134c55fe46a755d370bd007df725e03

commit d420b69b8134c55fe46a755d370bd007df725e03
Author: Paul Eggert <[email protected]>
Date:   Wed May 13 11:08:35 2026 -0700

    Simplify tzdb-related configuration
    
    tzdb 2026b no longer needs -Wno-discarded-qualifiers or
    -Wno-unused-variable.  From a suggestion by Joseph Myers in:
    https://sourceware.org/pipermail/libc-alpha/2026-May/177312.html
    * configure.ac (config-cflags-wno-discarded-qualifiers): Remove.
    * timezone/Makefile (CFLAGS-zic.c): Remove -Wno-unused-variable,
    $(config-cflags-wno-discarded-qualifiers).
    
    Reviewed-by: Adhemerval Zanella  <[email protected]>

Diff:
---
 configure.ac      | 16 ----------------
 timezone/Makefile |  7 +------
 2 files changed, 1 insertion(+), 22 deletions(-)

diff --git a/configure.ac b/configure.ac
index 280ec8e5b3..e9138a38b7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1371,22 +1371,6 @@ LIBC_TRY_CC_OPTION([-fpie], [libc_cv_fpie=yes], [libc_cv_fpie=no])
 
 AC_SUBST(libc_cv_fpie)
 
-dnl Check how to suppress C23-qualifier-generic const warnings.  GCC has
-dnl -Wno-discarded-qualifiers, while clang -Wno-incompatible-pointer-types-discards-qualifiers
-AC_CACHE_CHECK(for -Wno-discarded-qualifiers, libc_cv_cflags_wno_discarded_qualifiers, [dnl
-LIBC_TRY_CC_OPTION([-Werror -Wno-discarded-qualifiers],
-		   [libc_cv_cflags_wno_discarded_qualifiers=-Wno-discarded-qualifiers],
-		   [libc_cv_cflags_wno_discarded_qualifiers=])
-if test -z "$libc_cv_cflags_wno_discarded_qualifiers"; then
-  LIBC_TRY_CC_OPTION([-Werror -Wno-incompatible-pointer-types-discards-qualifiers],
-		     [libc_cv_cflags_wno_incompatible_pointer_type_discards_qualifiers=-Wno-incompatible-pointer-types-discards-qualifiers],
-		     [libc_cv_cflags_wno_incompatible_pointer_type_discards_qualifiers=])
-  libc_cv_cflags_wno_discarded_qualifiers=$libc_cv_cflags_wno_incompatible_pointer_type_discards_qualifiers
-fi
-])
-LIBC_CONFIG_VAR([config-cflags-wno-discarded-qualifiers],
-		[$libc_cv_cflags_wno_discarded_qualifiers])
-
 AC_CACHE_CHECK(for GLOB_DAT reloc,
 	       libc_cv_has_glob_dat, [dnl
 cat > conftest.c <<EOF
diff --git a/timezone/Makefile b/timezone/Makefile
index 386731ab99..426061737a 100644
--- a/timezone/Makefile
+++ b/timezone/Makefile
@@ -70,13 +70,8 @@ tz-cflags = -DTZDIR='"$(zonedir)"' \
 	    -DHAVE_GETTEXT -DUSE_LTZ=0 -D_ISOMAC -DTZ_DOMAIN='"libc"' \
 	    -include $(common-objpfx)config.h $(config-cflags-wno-maybe-uninitialized)
 
-# The -Wno-unused-variable flag is used to prevent GCC 6
-# from warning about time_t_min and time_t_max which are
-# defined in private.h but not used.
-# $(config-cflags-wno-discarded-qualifiers) is because zic is not prepared for C23
-# -qualifier-generic strchr.
 CFLAGS-zdump.c += $(tz-cflags)
-CFLAGS-zic.c += $(tz-cflags) -Wno-unused-variable $(config-cflags-wno-discarded-qualifiers)
+CFLAGS-zic.c += $(tz-cflags)
 
 # We have to make sure the data for testing the tz functions is available.
 # Don't add leapseconds here since test-tz made checks that work only without