bpo-34652: Use AC_CHECK_FUNCS for lchmod. (GH-12799)

A fix for 69e96910, which resulted in lchmod being disabled on all platforms, not just Linux.

(cherry picked from commit ed709d56)

configure

@@ -10632,10 +10632,16 @@ done
 # links. Some libc implementations have a stub lchmod implementation that always
 # returns an error.
 if test "$MACHDEP" != linux; then
+  for ac_func in lchmod
+do :
   ac_fn_c_check_func "$LINENO" "lchmod" "ac_cv_func_lchmod"
 if test "x$ac_cv_func_lchmod" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_LCHMOD 1
+_ACEOF
 
 fi
+done
 
 fi
 

configure.ac

@@ -3138,7 +3138,7 @@ AC_CHECK_FUNCS(alarm setitimer getitimer bind_textdomain_codeset chown \
 # links. Some libc implementations have a stub lchmod implementation that always
 # returns an error.
 if test "$MACHDEP" != linux; then
-  AC_CHECK_FUNC(lchmod)
+  AC_CHECK_FUNCS(lchmod)
 fi
 
 # For some functions, having a definition is not sufficient, since

pyconfig.h.in

@@ -439,6 +439,9 @@
 /* Define to 1 if you have the 'lchflags' function. */
 #undef HAVE_LCHFLAGS
 
+/* Define to 1 if you have the `lchmod' function. */
+#undef HAVE_LCHMOD
+
 /* Define to 1 if you have the `lchown' function. */
 #undef HAVE_LCHOWN