Upgrade to autoconf 2.5x.

m4/uintmax_t.m4

@@ -2,21 +2,18 @@
 
 dnl From Paul Eggert.
 
-AC_PREREQ(2.13)
+AC_PREREQ(2.50)
 
 # Define uintmax_t to `unsigned long' or `unsigned long long'
 # if <inttypes.h> does not exist.
 
 AC_DEFUN(jm_AC_TYPE_UINTMAX_T,
 [
-  AC_REQUIRE([jm_AC_HEADER_INTTYPES_H])
-  if test $jm_ac_cv_header_inttypes_h = no; then
-    AC_REQUIRE([jm_AC_TYPE_UNSIGNED_LONG_LONG])
-    test $ac_cv_type_unsigned_long_long = yes \
-      && ac_type='unsigned long long' \
-      || ac_type='unsigned long'
-    AC_DEFINE_UNQUOTED(uintmax_t, $ac_type,
-[  Define to unsigned long or unsigned long long
-   if <inttypes.h> doesn't define.])
-  fi
+  AC_CHECK_TYPE(uintmax_t, ,
+    [AC_REQUIRE([jm_AC_TYPE_UNSIGNED_LONG_LONG])
+     test $ac_cv_type_unsigned_long_long = yes \
+       && ac_type='unsigned long long' \
+       || ac_type='unsigned long'
+     AC_DEFINE_UNQUOTED(uintmax_t, $ac_type,
+       [Define to the widest unsigned integer type if standard headers do not declare.])])
 ])