Fix localized display of date and time in the NS port

* src/nsterm.m (ns_init_locale): If not already set, set LC_ALL to the
current locale ID so that dates, currencies, etc. use the settings
configured in the operating system.  (Bug#51321)

src/nsterm.m

@@ -543,8 +543,10 @@ - (NSColor *)colorUsingDefaultColorSpace
       NSString *localeID = [NSString stringWithFormat:@"%@.UTF-8",
                                      [locale localeIdentifier]];
 
-      /* Set LANG to locale, but not if LANG is already set.  */
+      /* Set LANG and LC_ALL to locale, but not if the variables are
+         already set.  */
       setenv("LANG", [localeID UTF8String], 0);
+      setenv("LC_ALL", [localeID UTF8String], 0);
     }
   @catch (NSException *e)
     {