iphlpapi: _res is per-thread in glibc with pthreads

[Dan Kegel]

With test.  Without the fix, the test case crashes on my machine.
Fixes crash in bug http://bugs.winehq.org/show_bug.cgi?id=21624

Same fix probably needed in dnsapi, or maybe iphlpapi should
use dnsapi rather than unix dns api.

Thanks to AF for the analysis.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ip.patch
Type: text/x-patch
Size: 2861 bytes
Desc: not available
URL: <http://www.winehq.org/pipermail/wine-patches/attachments/20100207/8d027034/attachment.bin>