[PATCH] Fix -Wdeprecated-non-prototype in configure

[Sam James]

Fixes the following with Clang 16:
```
-warning: a function definition without a prototype is deprecated in all 
versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
+error: a function definition without a prototype is deprecated in all versions 
of C and is not supported in C2x [-Werror,-Wdeprecated-non-prototype]
 int foo(i)
     ^
```
---
 m4/labels-as-values.m4 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/m4/labels-as-values.m4 b/m4/labels-as-values.m4
index e01768f00..f2f38858e 100644
--- a/m4/labels-as-values.m4
+++ b/m4/labels-as-values.m4
@@ -2,7 +2,7 @@ dnl check for gcc's "labels as values" feature
 AC_DEFUN([AC_C_LABELS_AS_VALUES],
 [AC_CACHE_CHECK([labels as values], ac_cv_labels_as_values,
 [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
-int foo(int);
+int foo(int i);
 int foo(int i) {
 static void *label[] = { &&l1, &&l2 };
 goto *label[i];
-- 
2.38.1