Remove g_mbstowcs() and g_wcstombs()

These calls are now replaced with explicit UTF conversion routines in
the common/string_calls.[hc] and common/parse.[hc] modules.

Also removed:-
- The support code in common/os_calls.c to set the locale to use
  these routines.
- The twchar type in arch.h

common/arch.h

@@ -145,12 +145,10 @@ typedef bool_t tbool;
 typedef intptr_t tbus;
 typedef intptr_t tintptr;
 
-/* wide char, socket */
+/* socket */
 #if defined(_WIN32)
-typedef unsigned short twchar;
 typedef unsigned int tsock;
 #else
-typedef int twchar;
 typedef int tsock;
 #endif
 #endif /* DEFINED_Ts */

common/os_calls.c

@@ -181,20 +181,6 @@ g_init(const char *app_name)
 
     WSAStartup(2, &wsadata);
 #endif
-
-    /* In order to get g_mbstowcs and g_wcstombs to work properly with
-       UTF-8 non-ASCII characters, LC_CTYPE cannot be "C" or blank.
-       To select UTF-8 encoding without specifying any countries/languages,
-       "C.UTF-8" is used but provided in few systems.
-
-       See also: https://sourceware.org/glibc/wiki/Proposals/C.UTF-8 */
-    char *lc_ctype;
-    lc_ctype = setlocale(LC_CTYPE, "C.UTF-8");
-    if (lc_ctype == NULL)
-    {
-        /* use en_US.UTF-8 instead if not available */
-        setlocale(LC_CTYPE, "en_US.UTF-8");
-    }
 }
 
 /*****************************************************************************/

common/string_calls.c

@@ -710,30 +710,6 @@ g_strstr(const char *haystack, const char *needle)
     return (char *)strstr(haystack, needle);
 }
 
-/*****************************************************************************/
-int
-g_mbstowcs(twchar *dest, const char *src, int n)
-{
-    wchar_t *ldest;
-    int rv;
-
-    ldest = (wchar_t *)dest;
-    rv = mbstowcs(ldest, src, n);
-    return rv;
-}
-
-/*****************************************************************************/
-int
-g_wcstombs(char *dest, const twchar *src, int n)
-{
-    const wchar_t *lsrc;
-    int rv;
-
-    lsrc = (const wchar_t *)src;
-    rv = wcstombs(dest, lsrc, n);
-    return rv;
-}
-
 /*****************************************************************************/
 /* returns error */
 int

common/string_calls.h

@@ -310,8 +310,6 @@ int      g_bytes_to_hexstr(const void *bytes, int num_bytes, char *out_str,
                            int bytes_out_str);
 int      g_pos(const char *str, const char *to_find);
 char    *g_strstr(const char *haystack, const char *needle);
-int      g_mbstowcs(twchar *dest, const char *src, int n);
-int      g_wcstombs(char *dest, const twchar *src, int n);
 
 /** trim spaces and tabs, anything <= space
  *