pythongh-128354: Consistently use LIBS over LDFLAGS in library build checks (python#128359)

Author: zanieb

configure

@@ -3701,7 +3701,7 @@ AS_VAR_IF([have_uuid], [missing], [
     ], [
       WITH_SAVE_ENV([
         CPPFLAGS="$CPPFLAGS $LIBUUID_CFLAGS"
-        LDFLAGS="$LDFLAGS $LIBUUID_LIBS"
+        LIBS="$LIBS $LIBUUID_LIBS"
         AC_CHECK_HEADERS([uuid/uuid.h], [
           PY_CHECK_LIB([uuid], [uuid_generate_time], [have_uuid=yes])
           PY_CHECK_LIB([uuid], [uuid_generate_time_safe],
@@ -3971,7 +3971,7 @@ AS_VAR_IF([have_libffi], [missing], [
   PKG_CHECK_MODULES([LIBFFI], [libffi], [have_libffi=yes], [
     WITH_SAVE_ENV([
       CPPFLAGS="$CPPFLAGS $LIBFFI_CFLAGS"
-      LDFLAGS="$LDFLAGS $LIBFFI_LIBS"
+      LIBS="$LIBS $LIBFFI_LIBS"
       AC_CHECK_HEADER([ffi.h], [
         AC_CHECK_LIB([ffi], [ffi_call], [
           have_libffi=yes
@@ -4005,8 +4005,8 @@ AS_VAR_IF([have_libffi], [yes], [
   AS_VAR_IF([ac_cv_lib_dl_dlopen], [yes], [AS_VAR_APPEND([LIBFFI_LIBS], [" -ldl"])])
 
   WITH_SAVE_ENV([
-    CFLAGS="$LIBFFI_CFLAGS $CFLAGS"
-    LDFLAGS="$LIBFFI_LIBS $LDFLAGS"
+    CFLAGS="$CFLAGS $LIBFFI_CFLAGS"
+    LIBS="$LIBS $LIBFFI_LIBS"
 
     PY_CHECK_FUNC([ffi_prep_cif_var], [@%:@include <ffi.h>])
     PY_CHECK_FUNC([ffi_prep_closure_loc], [@%:@include <ffi.h>])
@@ -4021,9 +4021,8 @@ AS_VAR_IF([have_libffi], [yes], [
 #
 AC_CACHE_CHECK([libffi has complex type support], [ac_cv_ffi_complex_double_supported],
 [WITH_SAVE_ENV([
- CPPFLAGS="$LIBFFI_CFLAGS $CPPFLAGS"
- LDFLAGS="$LIBFFI_LIBS $LDFLAGS"
- LIBS="$LIBFFI_LIBS $LIBS"
+ CPPFLAGS="$CPPFLAGS $LIBFFI_CFLAGS"
+ LIBS="$LIBS $LIBFFI_LIBS"
 AC_RUN_IFELSE([AC_LANG_SOURCE([[
 #include <complex.h>
 #include <ffi.h>
@@ -4086,8 +4085,8 @@ AS_VAR_IF(
 
 AS_VAR_IF([with_system_libmpdec], [yes],
   [WITH_SAVE_ENV([
-    CPPFLAGS="$LIBMPDEC_CFLAGS $CPPFLAGS"
-    LIBS="$LIBMPDEC_LIBS $LIBS"
+    CPPFLAGS="$CPPFLAGS $LIBMPDEC_CFLAGS"
+    LIBS="$LIBS $LIBMPDEC_LIBS"
 
     AC_LINK_IFELSE([
       AC_LANG_PROGRAM([
@@ -4220,7 +4219,7 @@ WITH_SAVE_ENV([
 dnl bpo-45774/GH-29507: The CPP check in AC_CHECK_HEADER can fail on FreeBSD,
 dnl hence CPPFLAGS instead of CFLAGS.
   CPPFLAGS="$CPPFLAGS $LIBSQLITE3_CFLAGS"
-  LIBS="$LIBSQLITE3_LIBS $LIBS"
+  LIBS="$LIBS $LIBSQLITE3_LIBS"
 
   AC_CHECK_HEADER([sqlite3.h], [
     have_sqlite3=yes
@@ -4323,7 +4322,7 @@ AS_CASE([$ac_sys_system],
 
 WITH_SAVE_ENV([
   CPPFLAGS="$CPPFLAGS $TCLTK_CFLAGS"
-  LIBS="$TCLTK_LIBS $LDFLAGS"
+  LIBS="$LIBS $TCLTK_LIBS"
 
   AC_LINK_IFELSE([
     AC_LANG_PROGRAM([
@@ -4365,7 +4364,7 @@ AC_ARG_VAR([GDBM_CFLAGS], [C compiler flags for gdbm])
 AC_ARG_VAR([GDBM_LIBS], [additional linker flags for gdbm])
 WITH_SAVE_ENV([
   CPPFLAGS="$CPPFLAGS $GDBM_CFLAGS"
-  LDFLAGS="$GDBM_LIBS $LDFLAGS"
+  LIBS="$LIBS $GDBM_LIBS"
   AC_CHECK_HEADERS([gdbm.h], [
     AC_CHECK_LIB([gdbm], [gdbm_open], [
       have_gdbm=yes
@@ -5310,7 +5309,7 @@ PKG_CHECK_MODULES([ZLIB], [zlib >= 1.2.0], [
 ], [
   WITH_SAVE_ENV([
     CPPFLAGS="$CPPFLAGS $ZLIB_CFLAGS"
-    LDFLAGS="$LDFLAGS $ZLIB_LIBS"
+    LIBS="$LIBS $ZLIB_LIBS"
     AC_CHECK_HEADERS([zlib.h], [
       PY_CHECK_LIB([z], [gzread], [have_zlib=yes], [have_zlib=no])
     ], [have_zlib=no])
@@ -5334,7 +5333,7 @@ PY_CHECK_EMSCRIPTEN_PORT([BZIP2], [-sUSE_BZIP2])
 PKG_CHECK_MODULES([BZIP2], [bzip2], [have_bzip2=yes], [
   WITH_SAVE_ENV([
     CPPFLAGS="$CPPFLAGS $BZIP2_CFLAGS"
-    LDFLAGS="$LDFLAGS $BZIP2_LIBS"
+    LIBS="$LIBS $BZIP2_LIBS"
     AC_CHECK_HEADERS([bzlib.h], [
       AC_CHECK_LIB([bz2], [BZ2_bzCompress], [have_bzip2=yes], [have_bzip2=no])
     ], [have_bzip2=no])
@@ -5348,7 +5347,7 @@ PKG_CHECK_MODULES([BZIP2], [bzip2], [have_bzip2=yes], [
 PKG_CHECK_MODULES([LIBLZMA], [liblzma], [have_liblzma=yes], [
   WITH_SAVE_ENV([
     CPPFLAGS="$CPPFLAGS $LIBLZMA_CFLAGS"
-    LDFLAGS="$LDFLAGS $LIBLZMA_LIBS"
+    LIBS="$LIBS $LIBLZMA_LIBS"
     AC_CHECK_HEADERS([lzma.h], [
       AC_CHECK_LIB([lzma], [lzma_easy_encoder], [have_liblzma=yes], [have_liblzma=no])
     ], [have_liblzma=no])
@@ -6342,7 +6341,7 @@ AS_VAR_IF([with_readline], [readline], [
   ], [
     WITH_SAVE_ENV([
       CPPFLAGS="$CPPFLAGS $LIBREADLINE_CFLAGS"
-      LDFLAGS="$LDFLAGS $LIBREADLINE_LIBS"
+      LIBS="$LIBS $LIBREADLINE_LIBS"
       AC_CHECK_HEADERS([readline/readline.h], [
         AC_CHECK_LIB([readline], [readline], [
           LIBREADLINE=readline
@@ -6363,7 +6362,7 @@ AS_VAR_IF([with_readline], [edit], [
   ], [
     WITH_SAVE_ENV([
       CPPFLAGS="$CPPFLAGS $LIBEDIT_CFLAGS"
-      LDFLAGS="$LDFLAGS $LIBEDIT_LIBS"
+      LIBS="$LIBS $LIBEDIT_LIBS"
       AC_CHECK_HEADERS([editline/readline.h], [
         AC_CHECK_LIB([edit], [readline], [
           LIBREADLINE=edit
@@ -6387,7 +6386,7 @@ AS_VAR_IF([with_readline], [no], [
 
   WITH_SAVE_ENV([
     CPPFLAGS="$CPPFLAGS $READLINE_CFLAGS"
-    LIBS="$READLINE_LIBS $LIBS"
+    LIBS="$LIBS $READLINE_LIBS"
     LIBS_SAVE=$LIBS
 
     m4_define([readline_includes], [