rpcrt4: Hold the thread-data's critical section while cancelling a call.

[Robert Shearman]

Check that there is a connection before trying to cancel it.
---
  dlls/rpcrt4/rpcrt4_main.c |    4 +++-
  1 files changed, 3 insertions(+), 1 deletions(-)
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 80a330c4a388197359a4011ace4c89f78334bff2.diff
Type: text/x-patch
Size: 676 bytes
Desc: not available
Url : http://www.winehq.org/pipermail/wine-patches/attachments/20071118/75e6d374/attachment.bin