Let --enable-clocale=dragonfly work as a configure option

Author: Bill-Sommerfeld

libstdc++-v3/acinclude.m4

@@ -2774,7 +2774,7 @@ dnl
 AC_DEFUN([GLIBCXX_ENABLE_CLOCALE], [
   GLIBCXX_ENABLE(clocale,auto,[[[=MODEL]]],
     [use MODEL for target locale package],
-    [permit generic|gnu|ieee_1003.1-2001|newlib|yes|no|auto])
+    [permit generic|gnu|ieee_1003.1-2001|newlib|dragonfly|yes|no|auto])
 
   # Deal with gettext issues.  Default to not using it (=no) until we detect
   # support for it later.  Let the user turn it off via --e/d, but let that

libstdc++-v3/configure

@@ -16635,7 +16635,7 @@ $as_echo "stdio (with POSIX read/write)" >&6; }
 if test "${enable_clocale+set}" = set; then :
   enableval=$enable_clocale;
       case "$enableval" in
-       generic|gnu|ieee_1003.1-2001|newlib|yes|no|auto) ;;
+       generic|gnu|ieee_1003.1-2001|newlib|dragonfly|yes|no|auto) ;;
        *) as_fn_error $? "Unknown argument to enable/disable clocale" "$LINENO" 5 ;;
 	  	        esac