[patch libstdc++]: Add some missing errno-constants for mingw-targets

[Kai Tietz]

Hello,

this patch adds some errno values supported by newer runtime-version.
To keep backward compatibility
this patch checks for their definition before trying to use them.
Especially the EPERM error-number is required for having ISO-C++0x
std::thread support enabled with
winpthread libary for 32-bit and 64-bit Windows host.

ChangeLog

2011-08-28  Kai Tietz  <ktietz@redhat.com>

	* config/os/mingw32/error_constants.h (ECHILD): Add support,
	if present.
	(ENOSPC): Likewise.
	(EPERM): Likewise.

Bootstrapped and regression tested for x86_64-w64-mingw32 and
i686-w64-mingw32.  Ok for apply?

Regards,
Kai

Index: error_constants.h
===================================================================
--- error_constants.h	(revision 178096)
+++ error_constants.h	(working copy)
@@ -79,13 +79,17 @@
 //    network_reset = 				ENETRESET,
 //    network_unreachable = 			ENETUNREACH,
 //    no_buffer_space = 			ENOBUFS,
-//    no_child_process = 			ECHILD,
+#ifdef ECHILD
+      no_child_process = 			ECHILD,
+#endif
 //    no_link = 				ENOLINK,
       no_lock_available = 			ENOLCK,
 //    no_message_available = 			ENODATA,
 //    no_message = 				ENOMSG,
 //    no_protocol_option = 			ENOPROTOOPT,
-//    no_space_on_device = 			ENOSPC,
+#ifdef ENOSPC
+      no_space_on_device = 			ENOSPC,
+#endif
 //    no_stream_resources = 			ENOSR,
       no_such_device_or_address = 		ENXIO,
       no_such_device = 				ENODEV,
@@ -99,7 +103,9 @@
 //    not_supported = 				ENOTSUP,
 //    operation_canceled = 			ECANCELED,
 //    operation_in_progress = 			EINPROGRESS,
-//    operation_not_permitted = 		EPERM,
+#ifdef EPERM
+      operation_not_permitted = 		EPERM,
+#endif
 //    operation_not_supported = 		EOPNOTSUPP,
 //    operation_would_block = 			EWOULDBLOCK,
 //    owner_dead = 				EOWNERDEAD,