Don't set h_errno on MS-Windows except in gethostbyname.

See http://lists.gnu.org/archive/html/emacs-devel/2013-02/msg00293.html
and the following discussion for the details.

 src/w32.c (set_errno): Reset h_errno and don't set it to any other
 value.  Set errno instead.
 (check_errno): Reset h_errno.
 (sys_socket, socket_to_fd, sys_bind, sys_connect)
 (sys_gethostname, sys_getservbyname, sys_getpeername)
 (sys_shutdown, sys_setsockopt, sys_listen, sys_getsockname)
 (sys_accept, sys_recvfrom, sys_sendto, fcntl, sys_read): Don't set
 h_errno.
 (sys_gethostbyname): Set h_errno only errors detected.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 6ff25edac50..d326532ecb7 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,15 @@
+2013-02-16  Eli Zaretskii  <eliz@gnu.org>
+
+        * w32.c (set_errno): Reset h_errno and don't set it to any other
+        value.  Set errno instead.
+        (check_errno): Reset h_errno.
+        (sys_socket, socket_to_fd, sys_bind, sys_connect)
+        (sys_gethostname, sys_getservbyname, sys_getpeername)
+        (sys_shutdown, sys_setsockopt, sys_listen, sys_getsockname)
+        (sys_accept, sys_recvfrom, sys_sendto, fcntl, sys_read): Don't set
+        h_errno.
+        (sys_gethostbyname): Set h_errno only errors detected.
+
 2013-02-15  Paul Eggert  <eggert@cs.ucla.edu>
 
         * process.c (h_errno) [!HAVE_H_ERRNO]: Remove unused decl.