New signature for static fcn my_langinfo()

This commit changes the calling sequence for my_langinfo to add the
desired locale (or a sentinel to indicate to use the current locale),
and the locale category of the desired item.

This allows the function to be able to return the desired value for any
locale, avoiding some locale changes that would happen until this
commit, and hiding the need for locale changes from outside functions,
though a couple continue to do so to avoid potential multiple changes.

embed.fnc

@@ -3220,13 +3220,15 @@ ST	|unsigned int|get_category_index|const int category|NULLOK const char * local
 S	|const char*|switch_category_locale_to_template|const int switch_category|const int template_category|NULLOK const char * template_locale
 S	|void	|restore_switched_locale|const int category|NULLOK const char * const original_locale
 #    if defined(HAS_NL_LANGINFO) || defined(HAS_NL_LANGINFO_L)
-S	|const char*|my_langinfo|const nl_item item			\
-				|bool toggle				\
+S	|const char*|my_langinfo_i|const nl_item item			\
+				|const unsigned int cat_index		\
+				|NULLOK const char * locale		\
 				|NN const char ** retbufp		\
 				|NULLOK Size_t * retbuf_sizep
 #  else
-S	|const char*|my_langinfo|const int item				\
-				|bool toggle				\
+S	|const char*|my_langinfo_i|const int item			\
+				|const unsigned int cat_index		\
+				|NULLOK const char * locale		\
 				|NN const char ** retbufp		\
 				|NULLOK Size_t * retbuf_sizep
 #  endif

embed.h

@@ -1505,7 +1505,7 @@
 #  if !(defined(HAS_NL_LANGINFO) || defined(HAS_NL_LANGINFO_L))
 #    if defined(PERL_IN_LOCALE_C)
 #      if defined(USE_LOCALE)
-#define my_langinfo(a,b,c,d)	S_my_langinfo(aTHX_ a,b,c,d)
+#define my_langinfo_i(a,b,c,d,e)	S_my_langinfo_i(aTHX_ a,b,c,d,e)
 #      endif
 #    endif
 #  endif
@@ -1615,7 +1615,7 @@
 #  if defined(HAS_NL_LANGINFO) || defined(HAS_NL_LANGINFO_L)
 #    if defined(PERL_IN_LOCALE_C)
 #      if defined(USE_LOCALE)
-#define my_langinfo(a,b,c,d)	S_my_langinfo(aTHX_ a,b,c,d)
+#define my_langinfo_i(a,b,c,d,e)	S_my_langinfo_i(aTHX_ a,b,c,d,e)
 #      endif
 #    endif
 #  endif