locale.c: Collapse duplicate logic into one instance

The previous commit move the logic for localeconv() into locale.c.  This
commit takes advantage of that to use it instead of repeating the logic.

On Windows, there is alternative way of finding the radix character for
systems that have a localeconv() that could cause a race.  Prior to this
commit, if that failed to find something that looked like the radix, it
returned a '?'.  Now it will drop down to using this new code, as the
likelihood of the race is small.

Notably, this commit removes the inconsistent duplicate logic that had
been used to deal with the Windows broken localeconv() bug.

embed.fnc

@@ -3227,7 +3227,7 @@ S	|unsigned|get_locale_string_utf8ness_i				\
 				|const int known_utf8
 #    if (defined(HAS_LOCALECONV) || defined(HAS_LOCALECONV_L))		\
      && (defined(USE_LOCALE_MONETARY) || defined(USE_LOCALE_NUMERIC))
-S	|HV *	|my_localeconv
+S	|HV *	|my_localeconv|const int item
 S	|HV *	|populate_localeconv|NN const struct lconv *lcbuf	\
 				|const int numeric_locale_is_utf8	\
 				|const int monetary_locale_is_utf8
@@ -3244,6 +3244,13 @@ S	|const char*|my_langinfo_i|const int item			\
 				|NULLOK const char * locale		\
 				|NN const char ** retbufp		\
 				|NULLOK Size_t * retbuf_sizep
+#      if (defined(HAS_LOCALECONV) || defined(HAS_LOCALECONV_L))	\
+       && (defined(USE_LOCALE_MONETARY) || defined(USE_LOCALE_NUMERIC))
+S	|HV *	|get_nl_item_from_localeconv				\
+				|NN const struct lconv *lcbuf		\
+                                |const int item				\
+                                |const int unused
+#      endif
 #  endif
 STR	|const char *|save_to_buffer|NULLOK const char * string	\
 				    |NULLOK const char **buf	\

embed.h

@@ -1503,6 +1503,13 @@
 #    endif
 #  endif
 #  if !(defined(HAS_NL_LANGINFO) || defined(HAS_NL_LANGINFO_L))
+#    if (defined(HAS_LOCALECONV) || defined(HAS_LOCALECONV_L))	       && (defined(USE_LOCALE_MONETARY) || defined(USE_LOCALE_NUMERIC))
+#      if defined(PERL_IN_LOCALE_C)
+#        if defined(USE_LOCALE)
+#define get_nl_item_from_localeconv(a,b,c)	S_get_nl_item_from_localeconv(aTHX_ a,b,c)
+#        endif
+#      endif
+#    endif
 #    if defined(PERL_IN_LOCALE_C)
 #      if defined(USE_LOCALE)
 #define my_langinfo_i(a,b,c,d,e)	S_my_langinfo_i(aTHX_ a,b,c,d,e)
@@ -1575,7 +1582,7 @@
 #  if (defined(HAS_LOCALECONV) || defined(HAS_LOCALECONV_L))		     && (defined(USE_LOCALE_MONETARY) || defined(USE_LOCALE_NUMERIC))
 #    if defined(PERL_IN_LOCALE_C)
 #      if defined(USE_LOCALE)
-#define my_localeconv()		S_my_localeconv(aTHX)
+#define my_localeconv(a)	S_my_localeconv(aTHX_ a)
 #define populate_localeconv(a,b,c)	S_populate_localeconv(aTHX_ a,b,c)
 #      endif
 #    endif