[8u] RFR: 8150688: Fix os_windows siglabel

[Kevin Walls]

Hi,

I'd like to get a review of this backport from 9 to 8u:

8150688: Fix os_windows siglabel
JBS:https://bugs.openjdk.java.net/browse/JDK-8150688

9 changeset:
URL:http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/80706cc25494

9 review thread:
http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2016-March/018236.html

Proposed 8u change:http://cr.openjdk.java.net/~kevinw/8150688/webrev.00/

This is a pretty clean backport. but didn't import automatically: in 8u
there is no "os::get_signal_number()" and some of the def_excpt... lines
didn't apply automatically, but they are the same change.

This removes some errors when varying the windows compiler in use, still
builds and tests OK on current standard VS compiler.

Thanks!
Kevin