Include <wchar.h> for towlower, towupper, to avoid implicit function

declarations and build failures with future compilers.

Submitted upstream: <https://sourceforge.net/p/dc3dd/bugs/22/>

diff --git a/configure b/configure

index 1901a37..5a4b0c3

--- a/configure

+++ b/configure

@@ -54147,6 +54147,7 @@ cat >>conftest.$ac_ext <<_ACEOF

 #endif

 #include <stdlib.h>

 #include <string.h>

+#include <wctype.h>

 struct tm t;

 char buf[16];

 int main () {

@@ -54913,6 +54914,7 @@ cat >>conftest.$ac_ext <<_ACEOF

 #endif

 #include <stdlib.h>

 #include <string.h>

+#include <wctype.h>

 struct tm t;

 char buf[16];

 int main () {

diff --git a/m4/locale-tr.m4 b/m4/locale-tr.m4

index d6a2088..d92c674 100644

--- a/m4/locale-tr.m4

+++ b/m4/locale-tr.m4

@@ -20,6 +20,7 @@ changequote(,)dnl

 #endif

 #include <stdlib.h>

 #include <string.h>

+#include <wctype.h>

 struct tm t;

 char buf[16];

 int main () {